lunes 19 de noviembre de 2007
domingo 18 de noviembre de 2007
INVESTIGACION DE CAMPO
PROYECTO AGATHA
REALIZADO POR: CLAUDIA MARCELA MURILLO
ELABORACION DE TALLA Y CALIBRACION DE ESMERALDAS COLOMBIANAS
EL COMERCIO DE LAS ESMERALDAS
Las esmeraldas pasan por numerosas manos en un viaje que incrementa su valor y su belleza. El comercio de una esmeralda tiene su inicio a mas de 400 Km. de la avenida Jiménez en medio de los ecos de un socavón, los mineros van en busca de alguna veta, un par de cámaras de seguridad los vigila cada minuto entre la negrura del túnel, cuando aparece el destello de una veta, todo se queda en total quietud ya que los dueños de las minas conocen las mañas de sus operarios ya que saben que suelen anunciar las vetas cuando ya les han arrancado suficientes piedras para venderlas en el mercado ilícito. De estos socavones salen las piedras verdes en bruto como la naturaleza la entrega, de allí se sigue el camino legal, el dueño de la mina las ofrece a los intermediarios del emerald trade center, quienes las cortaran, las tallaran y las comercializaran con otros intermediarios extranjeros.
Las gemas que logran extraer ilegalmente los operarios de las minas y los guaqueros que rastrillan los desechos de las minas, estas esmeraldas se comercializan en el mercado negro a baja voz, en la esquina de la Jiménez con séptima el llamado distrito verde se reúnen día a día docenas de vendedores de esmeraldas que muestran sus piedras tímida mente y allí en la calle envueltas en sobres de papel suelen ser despojos “piedras de poca monta”.
¿Cuál es el valor de la esmeralda según su color y tamaño?
- el valor de la esmeralda varia según su tamaño color, pureza y talla. Por esto un quilate de muy buena calidad puede llegar a tranzarse en 50.000 dólares y en los corrillos se habla de piedras de hasta 2000 quilates. Tan grandes como una botella.
- Por ejemplo este lote oscila entre 700.000. por la calidad, en su color, luz, pureza y talla.
Las buenas esmeraldas son costosas, así que desconfié de las que ofrezcan a precios bajos ya que podrían tratarse de falsificaciones que abundan en el mercado.
¿Cómo es el mercado internacional de la esmeralda?
A principio de los noventa el modo de explotación de esmeralda se ha regulado y la extracción se realiza en un modo más masivo ya que la codiciada gema empieza a escasear, esto hace que los precios aumenten en un 60% a productores de menos volumen y poca calidad como Pakistán, Afganistán, Madagascar y Rusia.
¿Quiénes son las personas que mas compran esmeraldas?
Una vez talladas las esmeraldas son ofrecidas a los joyeros encargados de engastarlas en algún metal que permita lucir su belleza y de allí al cuello de una mujer.
También son los comerciantes, quienes logran subir su valor mediante el trabajo realizado en ellas. Las cuales muchas de las veces terminan en manos de extranjeros. Y en las joyerías mas prestigiosas del mundo.
¿Es mas fácil venderlas talladas o en bruto?
En el mercado nacional se ven talladores expertos que pueden llegar a cobrar hasta un millón de pesos por quilate tallado, por eso los buenos talladores son escasos como las piedras mismas, la clave es que la esmeralda muestre su majestuoso color verde para resaltar su belleza. Por esto su valor se incrementa al estar talladas, claro que algunos extranjeros prefieren comprar la piedra en bruto ya que en el mercado internacional se encuentran talladores los cuales no trabajan por calidad si no por cantidad y esto hace que el valor aumente en el mercado.
También su nivel comercial se incrementa al ya estar engastada en una joya.
¿Cuales con las minas mas importantes?
Actualmente las zonas de minerías de esmeraldas en el Pals están ubicadas en el rectángulo esmeraldifero, un área de 200 Km de largo y 50 de ancho que toca 2 departamentos, los epicentros de producción son Muzu, Pita y Coscues en Boyacá. Y Chobor, Tancha y Gachala al oriente de Cundinamarca, estas pese a encontrarse a cientos de Km de distancia, comparte la misma falla geológica, por eso las esmeraldas que de allí se extraen poseen una calidad similar.
REALIZADO POR: CLAUDIA MARCELA MURILLO
ELABORACION DE TALLA Y CALIBRACION DE ESMERALDAS COLOMBIANAS
EL COMERCIO DE LAS ESMERALDAS
Las esmeraldas pasan por numerosas manos en un viaje que incrementa su valor y su belleza. El comercio de una esmeralda tiene su inicio a mas de 400 Km. de la avenida Jiménez en medio de los ecos de un socavón, los mineros van en busca de alguna veta, un par de cámaras de seguridad los vigila cada minuto entre la negrura del túnel, cuando aparece el destello de una veta, todo se queda en total quietud ya que los dueños de las minas conocen las mañas de sus operarios ya que saben que suelen anunciar las vetas cuando ya les han arrancado suficientes piedras para venderlas en el mercado ilícito. De estos socavones salen las piedras verdes en bruto como la naturaleza la entrega, de allí se sigue el camino legal, el dueño de la mina las ofrece a los intermediarios del emerald trade center, quienes las cortaran, las tallaran y las comercializaran con otros intermediarios extranjeros.
Las gemas que logran extraer ilegalmente los operarios de las minas y los guaqueros que rastrillan los desechos de las minas, estas esmeraldas se comercializan en el mercado negro a baja voz, en la esquina de la Jiménez con séptima el llamado distrito verde se reúnen día a día docenas de vendedores de esmeraldas que muestran sus piedras tímida mente y allí en la calle envueltas en sobres de papel suelen ser despojos “piedras de poca monta”.
¿Cuál es el valor de la esmeralda según su color y tamaño?
- el valor de la esmeralda varia según su tamaño color, pureza y talla. Por esto un quilate de muy buena calidad puede llegar a tranzarse en 50.000 dólares y en los corrillos se habla de piedras de hasta 2000 quilates. Tan grandes como una botella.
- Por ejemplo este lote oscila entre 700.000. por la calidad, en su color, luz, pureza y talla.
Las buenas esmeraldas son costosas, así que desconfié de las que ofrezcan a precios bajos ya que podrían tratarse de falsificaciones que abundan en el mercado.
¿Cómo es el mercado internacional de la esmeralda?
A principio de los noventa el modo de explotación de esmeralda se ha regulado y la extracción se realiza en un modo más masivo ya que la codiciada gema empieza a escasear, esto hace que los precios aumenten en un 60% a productores de menos volumen y poca calidad como Pakistán, Afganistán, Madagascar y Rusia.
¿Quiénes son las personas que mas compran esmeraldas?
Una vez talladas las esmeraldas son ofrecidas a los joyeros encargados de engastarlas en algún metal que permita lucir su belleza y de allí al cuello de una mujer.
También son los comerciantes, quienes logran subir su valor mediante el trabajo realizado en ellas. Las cuales muchas de las veces terminan en manos de extranjeros. Y en las joyerías mas prestigiosas del mundo.
¿Es mas fácil venderlas talladas o en bruto?
En el mercado nacional se ven talladores expertos que pueden llegar a cobrar hasta un millón de pesos por quilate tallado, por eso los buenos talladores son escasos como las piedras mismas, la clave es que la esmeralda muestre su majestuoso color verde para resaltar su belleza. Por esto su valor se incrementa al estar talladas, claro que algunos extranjeros prefieren comprar la piedra en bruto ya que en el mercado internacional se encuentran talladores los cuales no trabajan por calidad si no por cantidad y esto hace que el valor aumente en el mercado.
También su nivel comercial se incrementa al ya estar engastada en una joya.
¿Cuales con las minas mas importantes?
Actualmente las zonas de minerías de esmeraldas en el Pals están ubicadas en el rectángulo esmeraldifero, un área de 200 Km de largo y 50 de ancho que toca 2 departamentos, los epicentros de producción son Muzu, Pita y Coscues en Boyacá. Y Chobor, Tancha y Gachala al oriente de Cundinamarca, estas pese a encontrarse a cientos de Km de distancia, comparte la misma falla geológica, por eso las esmeraldas que de allí se extraen poseen una calidad similar.
Gem Cutting Instructions - Step by Step
Step
Description
Instructions
Pictures
1
Prep Gem Rough
Once you've picked your gem rough, you'll need to orient it for the best results when cutting. Whole chapters or books can be written on this topic, so we'll save that for next time! After orienting your rough, you'll cut a flat surface where the table will be. This will make it easier to apply dop wax and put the gem rough on a dop for cutting.
2
Prep Alcohol Burner
Okay, most of you already know how to setup your alcohol lamp, but here it is for posterity. Put the denatured alcohol into the alcohol burner, put the top back on and light it up!
3
Warm the Dop, Dop Wax, and the Rough
With the flame going, you can warm up the dop, warm up the rough a little bit not too much, and melt some wax onto the rough and onto the dop. Put the dop and the rough together at the waxy parts and precisely position the rough on the dop to cut for best yield. Usually you'll start with a flat dop that attaches to the table of the stone. When you flip the stone over you may use a v-shaped dop or a cone-shaped dop depending on the design you're cutting and the shape that it gives the pavilion.
Wait for Wax to Cool
Wait for the wax to completely cool. Once it is cool to the touch, very gently twist on rough and very gently tug it side to side to verify that the wax adhesion is strong enough for work.It takes a lot of practice to really figure out how much twisting and tugging is just enough to verify the wax is on good, so don't give up, just keep trying!
4
Put Dop in Quill
Now that your facet rough, dop wax, and dop are good friends, put the happy trio into the quill of your faceting machine. The quill is the liftable, turning, rotating, arm that holds the dop for cutting.
Set the Cutting Angle for the Quill
The cutting angle is determined by the faceting diagram you're using to cut your gem. At least I hope you're using a diagram! Otherwise you're doing an abstract and that works much better with an oil and canvas. Consult your faceting machine owner's manual if you're having trouble figuring out how to set the cutting angle for your machine.
Set the Index for the Quill
The indexes to cut to are determined by the faceting diagram you're using to cut your gem. Make sure you have the right index in the quill for the design you're cutting.
Adjust the height of the mast arm
Lower the quill arm to the lap. Adjust the mast arm height to the proper cutting depth for the specific facet that you are cutting. You'll want to start by cutting less than what you need to start with. This is because you'll cut this facet again, with subsequently finer laps until you finally polish the facet. So you always leave a little bit more material at each stage so that by the time you polish you'll have just the right depth on the facet. Determining the right depth for each coarseness or fineness of cutting is another one of those lessons best learned through experience.
5
Start Cutting
Okay, the cutting angle, the index and the mast height are set, and you've adjusted the height just right, right? Start cutting the stone but pressing lightly on the quill or the stone and moving it back and forth on the lap. This motion helps avoid overusing one area of the lap a
nd getting a groove.When cutting the stone you'll start with a coarse grit and move to finer grits until you have a mirror finish on every facet. The cutting levels are generally called preforming to get the basic gem shape, prepolishing to put a finer cut on each facet, and then the polish. Choosing which grits to use to cut through each stage to the finished product is a very highly debated topic that is best left to each faceter's discretion. But if you're looking for an opinion, I use 600 grit, 1200 grit, then cerium oxide to polish quartz. For harder materials I use 600 grit, 3000 grit, then 14,000 grit or 50,000 grit. If I'm really trying to impress, then I'll touch each facet with 100,000 grit at the end. I've heard that the final polish should be alumina oxide since it is a finer grade than 100k diamond but I have yet to try it.
6
Finished roughing in the main pavilion facet
The initial preform generally takes the first tier of facets or the median angle facet and cut until the facets meet at a point. This insures that there is enough gem rough to fully cut the design to the depth required. Technically you can save some rough by estimating or cutting exactly the amount needed to just allow the deepest tier of facets to meet but rarely is the rough so expensive to warrant saving a few points (one hundrenths of a carat) and going through that headache. Just cut till the facets meet and you'll have no worries!
7
Closer look at the pavilion preform
Another look at the main facets on the pavilion meeting
8
Roughed in the girdle for the gemstone
Once the three tiers of the pavilion have been preformed, then we will preform the girdle. The girdle is really important cause that is where gemstones are measured for setting in jewelry. Unless you're planning on never setting this gem or using custom jewelry, you will want to pull out your calipers to measure and cut the girdle to one of the major sizes that jewelry castings are available for. For example, 7x5mm or 8x10mm castings are widely available for oval or rectangle cuts.
Polishing Quartz using cerium oxide
The final polish for any gem requires special care. Unless you're an experienced faceter with plenty of broken in laps, you'll find this step will take a good bit of time and practice to learn. Any old hat who tells you otherwise... forgot! You can polish with diamond, cerium oxide, alumina oxide, or any number of brand name polishing laps that take a lot of the thinking out of the process. Just depends on your preference. A general rule of thumb is that softer abrasives like cerium are used for softer materials and harder abrasives are used for harder materials like topaz and sapphire.Professional and competition cutters will point out that ready to polish laps are softer and will round the facets on the gem when cutting. Harder laps that must be charged will cut flatter facets. Charging is when you put the diamond, cerium, or alumina powder, paste, or slurry onto the lap and wipe it into the lap.How can you tell a facet has been rounded? Reflect the light from an unshielded 20 or 40 watt bulb onto the facet. Be sure to put the bulb label reflection in so that you can see it on the facet. If it is curved (beyond the bulb curvature) then it is rounded. Some rounding is so severe that the light reflection can not be seen on the entire facet at once.
Smear the cerium oxide slurry on the phenolic lap
Once you have the dry cerium powder on the lap add water and smear the powder and water mixture on the lap. This is now called a slurry.
No really, smear it good!
Here is another pattern of spreading the slurry on the lap. Please take care that you don't get too distracted finger painting in the slurry and forget to finish polishing your gemstone!
Finished polishing pavilion of the gem
The pavilion of the gem has been polished using cerium oxide.
Another look at the polished pavilion
Here is another view of the polished pavilion.
Line up dop on transfer alignment fixture
Now that the pavilion is done, it is time to cut the crown. To do that we have to "flip" the rough on the dop and cut the other side. We have to remove the dop from the quill so that we can flip the stone over but you don't want to lose the positioning of the stone or it will be lopsided! We'll use a transfer alignment fixture to save our relative position so we can return to it after the transfer.Set the cutting angle to 90 degrees and the degree to the starting degree for the design. That is usually the highest number of the index gear you're using. Lower the mast height until the girdle facet brushes smoothly across the transfer alignment fixture. Make sure you always use the same grit lap so that your alignment fixture doesn't contaminate your laps.
Time to transfer from the pavilion to the crown of the gemstone
Remove the dop from the quill and put the dop into the dop transfer fixture. Pick out a dop that fits flush to the pavilion shape, in this case a v-shaped dop. You want a dop that is large enough to fully cover the culet and another tier or two of facets but not so large that it covers the girdle. When polishing the girdle we don't want to polish the dop too! With the two dops in the transfer fixture, light up the alcohol lamp and warm the new dop and melt some wax onto it. I like to melt some wax onto the pavilion of the stone too, as that helps with adhesion. However be very careful not to heat the stone too much or the original wax on the table dop will melt and the stone will shift around losing its place. That can also lead to a lopsided gemstone. With hot wax on the new dop and the stone's pavilion, push the two dops together firmly but not so much that you squeeze the wax out of the way.
Wait for the wax to cool
Wait for the wax to completely cool. Once it is cool to the touch, very gently twist on rough and very gently tug it side to side to verify that the wax adhesion is strong enough for work.It takes a lot of practice to really figure out how much twisting and tugging is just enough to verify the wax is on good, so don't give up, just keep trying!
Remove the old dop from the stone
Wrap a wet paper towel around the gem rough and the new dop. Heat the far end of the original dop until the heat travels through the dop and slowly melts the wax holding it to the table of the stone. The weight of the dop will pull it down from the stone as the wax begins to give and you can remove the heat. Using another paper towel or an oven mitt, pull off the original dop from the stone and very carefully remove any wax that you don't want gumming up your laps while you cut the crown.
Line up the dop in the quill to the transfer alignment fixture
Put the dop into the quill arm and lower the arm to the transfer alignment fixture. Gently turn the dop until the main girdle facet brushes smoothly across the transfer alignment fixture.
Put the dop back in the quill to prepare to cut the crown of the gem
Once the alignment is done, tighten the screw in the quill to hold the dop firmly in place.
Set the Cutting Angle for the Quill
The cutting angle is determined by the faceting diagram you're using to cut your gem. At least I hope you're using a diagram! Otherwise you're doing an abstract and that works much better with an oil and canvas. Consult your faceting machine owner's manual if you're having trouble figuring out how to set the cutting angle for your machine.
Each tier of the crown has been prepolished
I got ahead of myself! I meant to show you pictures of each tier getting preformed but I lost track of things and didn't come to my senses until just now. Here you see each tier has been preformed and prepolished.
Forgot to show the polished crown tiers!
Once I lost track and didn't get a chance to show you the polished crown tiers before moving to the table adapter.
Put table adapter in quill and line it up
With the crown facets all done except for the table we don't have to worry about using the transfer alignment fixture. We can just take the dop out of the quill and put the table adapter into the quill. The table adapter is needed for some faceting machines because they can not support setting the quill angle to zero degrees for the table facet. The adapter allows you to set the quill angle to 45 degrees and the stone will be at zero degrees from within the adapter. Rather than setting the quill angle to 45 degrees I prefer to put the adapter loosely into the quill, lower the mast height to the lap and when the adapter is flush to the lap and can be rotated smoothly, I tighten the quill angle screw, and then the quill screw for the adapter.
Put dop in table adapter.
With the table adapter fully prepped, place the dop into the table adapter and tighten it. There is no need to align anything. Be sure to raise the mast height up or if you drop the quill arm you could pop the stone off the dop right before your very last facet!
Cut the table of the crown of the gem
Now set the mast height so that you're cutting just into the table facet. Go slowly and cut cautiously so as not to over do it and put a big fat window into your gem and cut into the upper tier of facets.
Finished prepolishing the table of the gem
The table facet has been prepolished.
Finished polishing the table of the gem. A new gem is born!
The table facet has been polished and a new gemstone is born!
Remove dop from table adapter
Take the dop out of the table adapter and see what time it is. Mostly likely you've gone way past your bedtime!
Put dop in a dop holder
Put the dop in a holder so that you can melt the wax holding the gemstone onto it. I also recommend putting a wet paper towel around the stone to keep it cool.
Heat dop wax to release gem
Many faceters would disagree with this practice saying the heat could unnecessarily jeopardize the finished gem. True enough that a real expensive stone or one you've worked really hard on, you might want to skip this step
Remove excess wax from gemstone
If you've heated the dop to melt the wax then you've got some extra wax on the gemstone you can probably peel off with your fingers. Nothing stronger than that should be used to avoid marring the polish or the edges of the gemstone.
Put gem into acetone to remove remaining wax
Put the gemstone into acetone to remove the rest of the wax. You can put the gemstone on a dop in the acetone too, but try not to leave the dop in too long or it could get a slight skin on it from the acid eating away at it.
It really is in there!
Okay so my acetone is kinda dark and dirty but the gemstone is really in there!
The finished gemstone
Here is the finished gemstone! Hope you enjoyed the walkthrough!
Missing In Action
Hey! What did I miss? Let me know if some part of this walkthrough is confusing or is missing a step you want more information on. Drop me a note letting me know what else you would like for me to do a walkthrough for.
Step
Description
Instructions
Pictures
1
Prep Gem Rough
Once you've picked your gem rough, you'll need to orient it for the best results when cutting. Whole chapters or books can be written on this topic, so we'll save that for next time! After orienting your rough, you'll cut a flat surface where the table will be. This will make it easier to apply dop wax and put the gem rough on a dop for cutting.
2
Prep Alcohol Burner
Okay, most of you already know how to setup your alcohol lamp, but here it is for posterity. Put the denatured alcohol into the alcohol burner, put the top back on and light it up!
3
Warm the Dop, Dop Wax, and the Rough
With the flame going, you can warm up the dop, warm up the rough a little bit not too much, and melt some wax onto the rough and onto the dop. Put the dop and the rough together at the waxy parts and precisely position the rough on the dop to cut for best yield. Usually you'll start with a flat dop that attaches to the table of the stone. When you flip the stone over you may use a v-shaped dop or a cone-shaped dop depending on the design you're cutting and the shape that it gives the pavilion.
Wait for Wax to Cool
Wait for the wax to completely cool. Once it is cool to the touch, very gently twist on rough and very gently tug it side to side to verify that the wax adhesion is strong enough for work.It takes a lot of practice to really figure out how much twisting and tugging is just enough to verify the wax is on good, so don't give up, just keep trying!
4
Put Dop in Quill
Now that your facet rough, dop wax, and dop are good friends, put the happy trio into the quill of your faceting machine. The quill is the liftable, turning, rotating, arm that holds the dop for cutting.
Set the Cutting Angle for the Quill
The cutting angle is determined by the faceting diagram you're using to cut your gem. At least I hope you're using a diagram! Otherwise you're doing an abstract and that works much better with an oil and canvas. Consult your faceting machine owner's manual if you're having trouble figuring out how to set the cutting angle for your machine.
Set the Index for the Quill
The indexes to cut to are determined by the faceting diagram you're using to cut your gem. Make sure you have the right index in the quill for the design you're cutting.
Adjust the height of the mast arm
Lower the quill arm to the lap. Adjust the mast arm height to the proper cutting depth for the specific facet that you are cutting. You'll want to start by cutting less than what you need to start with. This is because you'll cut this facet again, with subsequently finer laps until you finally polish the facet. So you always leave a little bit more material at each stage so that by the time you polish you'll have just the right depth on the facet. Determining the right depth for each coarseness or fineness of cutting is another one of those lessons best learned through experience.
5
Start Cutting
Okay, the cutting angle, the index and the mast height are set, and you've adjusted the height just right, right? Start cutting the stone but pressing lightly on the quill or the stone and moving it back and forth on the lap. This motion helps avoid overusing one area of the lap a
nd getting a groove.When cutting the stone you'll start with a coarse grit and move to finer grits until you have a mirror finish on every facet. The cutting levels are generally called preforming to get the basic gem shape, prepolishing to put a finer cut on each facet, and then the polish. Choosing which grits to use to cut through each stage to the finished product is a very highly debated topic that is best left to each faceter's discretion. But if you're looking for an opinion, I use 600 grit, 1200 grit, then cerium oxide to polish quartz. For harder materials I use 600 grit, 3000 grit, then 14,000 grit or 50,000 grit. If I'm really trying to impress, then I'll touch each facet with 100,000 grit at the end. I've heard that the final polish should be alumina oxide since it is a finer grade than 100k diamond but I have yet to try it.6
Finished roughing in the main pavilion facet
The initial preform generally takes the first tier of facets or the median angle facet and cut until the facets meet at a point. This insures that there is enough gem rough to fully cut the design to the depth required. Technically you can save some rough by estimating or cutting exactly the amount needed to just allow the deepest tier of facets to meet but rarely is the rough so expensive to warrant saving a few points (one hundrenths of a carat) and going through that headache. Just cut till the facets meet and you'll have no worries!
7
Closer look at the pavilion preform
Another look at the main facets on the pavilion meeting
8
Roughed in the girdle for the gemstone
Once the three tiers of the pavilion have been preformed, then we will preform the girdle. The girdle is really important cause that is where gemstones are measured for setting in jewelry. Unless you're planning on never setting this gem or using custom jewelry, you will want to pull out your calipers to measure and cut the girdle to one of the major sizes that jewelry castings are available for. For example, 7x5mm or 8x10mm castings are widely available for oval or rectangle cuts.
Polishing Quartz using cerium oxide
The final polish for any gem requires special care. Unless you're an experienced faceter with plenty of broken in laps, you'll find this step will take a good bit of time and practice to learn. Any old hat who tells you otherwise... forgot! You can polish with diamond, cerium oxide, alumina oxide, or any number of brand name polishing laps that take a lot of the thinking out of the process. Just depends on your preference. A general rule of thumb is that softer abrasives like cerium are used for softer materials and harder abrasives are used for harder materials like topaz and sapphire.Professional and competition cutters will point out that ready to polish laps are softer and will round the facets on the gem when cutting. Harder laps that must be charged will cut flatter facets. Charging is when you put the diamond, cerium, or alumina powder, paste, or slurry onto the lap and wipe it into the lap.How can you tell a facet has been rounded? Reflect the light from an unshielded 20 or 40 watt bulb onto the facet. Be sure to put the bulb label reflection in so that you can see it on the facet. If it is curved (beyond the bulb curvature) then it is rounded. Some rounding is so severe that the light reflection can not be seen on the entire facet at once.
Smear the cerium oxide slurry on the phenolic lap
Once you have the dry cerium powder on the lap add water and smear the powder and water mixture on the lap. This is now called a slurry.
No really, smear it good!
Here is another pattern of spreading the slurry on the lap. Please take care that you don't get too distracted finger painting in the slurry and forget to finish polishing your gemstone!
Finished polishing pavilion of the gem
The pavilion of the gem has been polished using cerium oxide.
Another look at the polished pavilion
Here is another view of the polished pavilion.
Line up dop on transfer alignment fixture
Now that the pavilion is done, it is time to cut the crown. To do that we have to "flip" the rough on the dop and cut the other side. We have to remove the dop from the quill so that we can flip the stone over but you don't want to lose the positioning of the stone or it will be lopsided! We'll use a transfer alignment fixture to save our relative position so we can return to it after the transfer.Set the cutting angle to 90 degrees and the degree to the starting degree for the design. That is usually the highest number of the index gear you're using. Lower the mast height until the girdle facet brushes smoothly across the transfer alignment fixture. Make sure you always use the same grit lap so that your alignment fixture doesn't contaminate your laps.
Time to transfer from the pavilion to the crown of the gemstone
Remove the dop from the quill and put the dop into the dop transfer fixture. Pick out a dop that fits flush to the pavilion shape, in this case a v-shaped dop. You want a dop that is large enough to fully cover the culet and another tier or two of facets but not so large that it covers the girdle. When polishing the girdle we don't want to polish the dop too! With the two dops in the transfer fixture, light up the alcohol lamp and warm the new dop and melt some wax onto it. I like to melt some wax onto the pavilion of the stone too, as that helps with adhesion. However be very careful not to heat the stone too much or the original wax on the table dop will melt and the stone will shift around losing its place. That can also lead to a lopsided gemstone. With hot wax on the new dop and the stone's pavilion, push the two dops together firmly but not so much that you squeeze the wax out of the way.
Wait for the wax to cool
Wait for the wax to completely cool. Once it is cool to the touch, very gently twist on rough and very gently tug it side to side to verify that the wax adhesion is strong enough for work.It takes a lot of practice to really figure out how much twisting and tugging is just enough to verify the wax is on good, so don't give up, just keep trying!
Remove the old dop from the stone
Wrap a wet paper towel around the gem rough and the new dop. Heat the far end of the original dop until the heat travels through the dop and slowly melts the wax holding it to the table of the stone. The weight of the dop will pull it down from the stone as the wax begins to give and you can remove the heat. Using another paper towel or an oven mitt, pull off the original dop from the stone and very carefully remove any wax that you don't want gumming up your laps while you cut the crown.
Line up the dop in the quill to the transfer alignment fixture
Put the dop into the quill arm and lower the arm to the transfer alignment fixture. Gently turn the dop until the main girdle facet brushes smoothly across the transfer alignment fixture.
Put the dop back in the quill to prepare to cut the crown of the gem
Once the alignment is done, tighten the screw in the quill to hold the dop firmly in place.
Set the Cutting Angle for the Quill
The cutting angle is determined by the faceting diagram you're using to cut your gem. At least I hope you're using a diagram! Otherwise you're doing an abstract and that works much better with an oil and canvas. Consult your faceting machine owner's manual if you're having trouble figuring out how to set the cutting angle for your machine.
Each tier of the crown has been prepolished
I got ahead of myself! I meant to show you pictures of each tier getting preformed but I lost track of things and didn't come to my senses until just now. Here you see each tier has been preformed and prepolished.
Forgot to show the polished crown tiers!
Once I lost track and didn't get a chance to show you the polished crown tiers before moving to the table adapter.
Put table adapter in quill and line it up
With the crown facets all done except for the table we don't have to worry about using the transfer alignment fixture. We can just take the dop out of the quill and put the table adapter into the quill. The table adapter is needed for some faceting machines because they can not support setting the quill angle to zero degrees for the table facet. The adapter allows you to set the quill angle to 45 degrees and the stone will be at zero degrees from within the adapter. Rather than setting the quill angle to 45 degrees I prefer to put the adapter loosely into the quill, lower the mast height to the lap and when the adapter is flush to the lap and can be rotated smoothly, I tighten the quill angle screw, and then the quill screw for the adapter.
Put dop in table adapter.
With the table adapter fully prepped, place the dop into the table adapter and tighten it. There is no need to align anything. Be sure to raise the mast height up or if you drop the quill arm you could pop the stone off the dop right before your very last facet!
Cut the table of the crown of the gem
Now set the mast height so that you're cutting just into the table facet. Go slowly and cut cautiously so as not to over do it and put a big fat window into your gem and cut into the upper tier of facets.
Finished prepolishing the table of the gem
The table facet has been prepolished.
Finished polishing the table of the gem. A new gem is born!
The table facet has been polished and a new gemstone is born!
Remove dop from table adapter
Take the dop out of the table adapter and see what time it is. Mostly likely you've gone way past your bedtime!
Put dop in a dop holder
Put the dop in a holder so that you can melt the wax holding the gemstone onto it. I also recommend putting a wet paper towel around the stone to keep it cool.
Heat dop wax to release gem
Many faceters would disagree with this practice saying the heat could unnecessarily jeopardize the finished gem. True enough that a real expensive stone or one you've worked really hard on, you might want to skip this step
Remove excess wax from gemstone
If you've heated the dop to melt the wax then you've got some extra wax on the gemstone you can probably peel off with your fingers. Nothing stronger than that should be used to avoid marring the polish or the edges of the gemstone.
Put gem into acetone to remove remaining wax
Put the gemstone into acetone to remove the rest of the wax. You can put the gemstone on a dop in the acetone too, but try not to leave the dop in too long or it could get a slight skin on it from the acid eating away at it.
It really is in there!
Okay so my acetone is kinda dark and dirty but the gemstone is really in there!
The finished gemstone
Here is the finished gemstone! Hope you enjoyed the walkthrough!
Missing In Action
Hey! What did I miss? Let me know if some part of this walkthrough is confusing or is missing a step you want more information on. Drop me a note letting me know what else you would like for me to do a walkthrough for.
http://www.pietranobile.com.br/loja/Imagens/mina03.jpgEL MODELO DE LA MINERALIZACION DE ESMERALDAS
La mineralización está asociada a un episodio tectónico compresivo que afecta una formación de lutitas negras. Este episodio provoca el desarrollo sincrónico de pliegues y de cabalgamientos. Los planos de desplegadura, son utilizados como drenajes por fluidos calientes y ricos en elementos alcalinos. Esos fluidos tienen un origen evaporitica y provocan la albitizacion y la carbonatizacion de las rocas que encajonan y también la formación de una red de betas de extensión que han sido rellenadas por calcitas fibrosas.
La continuación de este intenso tetanismo compresional y el bloqueo frontal del movimiento desorganizan los pliegues y los cabalgamientos anteriores y forman nuevos pliegues en los cuales se desarrolla una deformación heterogénea que se exprime fuertemente dentro del corazón de los pliegues por un incremento de la presión de los fluidos que provocan la formación de plegamiento disarmonico, de brechas hidráulicas y de un segundo tipo de fracturas que han ido rellenadas por calcita en cristales.
Las consecuencias de un tal modo son muy importantes para la exploración y la explotación de la esmeralda. Así queda claro que los cabalgamientos son guías importantes de la mineralización de la esmeralda. Es muy probable que, cerca de esos cabalgamientos, se desarrollan pliegues asociados con vetas y brechas hidráulicas que son estructuras-trampas donde existen grandes posibilidades de almacenar esmeraldas.
La mineralización está asociada a un episodio tectónico compresivo que afecta una formación de lutitas negras. Este episodio provoca el desarrollo sincrónico de pliegues y de cabalgamientos. Los planos de desplegadura, son utilizados como drenajes por fluidos calientes y ricos en elementos alcalinos. Esos fluidos tienen un origen evaporitica y provocan la albitizacion y la carbonatizacion de las rocas que encajonan y también la formación de una red de betas de extensión que han sido rellenadas por calcitas fibrosas.
La continuación de este intenso tetanismo compresional y el bloqueo frontal del movimiento desorganizan los pliegues y los cabalgamientos anteriores y forman nuevos pliegues en los cuales se desarrolla una deformación heterogénea que se exprime fuertemente dentro del corazón de los pliegues por un incremento de la presión de los fluidos que provocan la formación de plegamiento disarmonico, de brechas hidráulicas y de un segundo tipo de fracturas que han ido rellenadas por calcita en cristales.
Las consecuencias de un tal modo son muy importantes para la exploración y la explotación de la esmeralda. Así queda claro que los cabalgamientos son guías importantes de la mineralización de la esmeralda. Es muy probable que, cerca de esos cabalgamientos, se desarrollan pliegues asociados con vetas y brechas hidráulicas que son estructuras-trampas donde existen grandes posibilidades de almacenar esmeraldas.
TIPOS DE ROCAS ENCONTRADOS EN LAS MINAS
Este parte comprendió un estudio de 14 secciones delgadas por medio del microscopio petrográfico e investigaciones geoquímicas por método de emisión-ICP para los elementos mayores y espectrometría de masa para las tierras raras y los elementos minores.
El presente informe estando orientado hacia la explotación, no se ha detallado el estudio microscópico de cada roca. Es mucho más importante para los ingenieros de la mina de saber a cual tipo de roca corresponde la roca encontrada en el corte y si hay posibilidades de encontrar esmeraldas dentro de la roca.
Este parte comprendió un estudio de 14 secciones delgadas por medio del microscopio petrográfico e investigaciones geoquímicas por método de emisión-ICP para los elementos mayores y espectrometría de masa para las tierras raras y los elementos minores.
El presente informe estando orientado hacia la explotación, no se ha detallado el estudio microscópico de cada roca. Es mucho más importante para los ingenieros de la mina de saber a cual tipo de roca corresponde la roca encontrada en el corte y si hay posibilidades de encontrar esmeraldas dentro de la roca.
LOCALIZACION
Las minas de esmeralda de muzo están localizadas al oeste del departamento de Boyacá en las estribaciones occidentales de la cordillera oriental de Colombia. La mina pertenece a la zona de reserva nacional de esmeraldas de muzo-cuscúes a 100 km al norte de Bogotá. Se encuentra en el anticlinorio de villeta donde aflora el cretáceo inferior. Es muy importante de notar que las minas de esmeralda en Colombia están ubicadas sobre los lados oeste y este de la cordillera oriental los cuales corresponden a zonas de cabalgamientos tectónico muy fuerte de la cuenca sedimentaria.
LOS TIPOS PRINCIPALES DE YACIMIENTOS ESMERALDIFEROS EN EL MUNDO
En el mundo hay dos tipos de yacimientos esmeraldiferos:
· Un tipo de alta temperatura que se caracterizan por la presencia de intrusiones graníticas y pegmaticas asociadas a rocas maficas y ultramaficas afectadas por las soluciones meta somáticas ricas en potasio y sodio. Este tipo de yacimiento es el más frecuente en el mundo. Los yacimientos del Brasil, describidos por Giuliano et al. Son de este tipo. La mineralización de esmeralda se encuentra dentro de intrusiones pegmaticas o vetas de cuarzo que cortan las secuencias Volcano-sedimentarias precámbricas.
· El tipo colombiano, de baja temperatura, asociado con las lutitos negras del cretáceo inferior, meta somatizadas por fluidos ricos en sodio y calcio. Este tipo es único en el mundo porque no es asociado con las rocas magma ticas. La mineralización está asociada con brechas tectónicas presentando un cemento que se compone de carbonatos, de pyrita y de albita. También, podemos encontrar las esmeraldas dentro de brechas hidráulicas o vetas de carbonatos.
Giuliano et al. Enseñan que los fluidos hidrotermales que son responsables del metasomatismo alcalino son aguas de cuenca sedimentaria que disolvieron niveles de evaporiticas. Además, Mc Laughlin y Arce estudiaron los diapiros salinos de zipaquira, tausa, nemocon, sesquile y Restrepo. Y mostraron que fluidos están cargados en elementos alcalinos durante la lixiviación de formaciones evaporiticas. Entonces, hay suertes que existen formaciones o diaporos de evaporitas, en o debajo las lutitos negras del cretáceo inferior.
BRILLO DE PIEDRAS - NOV 15 / 07
BRILLO DE PIEDRAS FACETEADAS:
1. Inicio por bisel
sujecion de la piedra , con el indice y el pulgar.
el brillo se determina por un sonido grave, eso quiere decir que empata bien la faceta con el disco ( disco de estaño y plomo) , previamente rayado con el bisturi para permitir resultados optimos del brillado.
el oido es el que determina que esta pasando con la piedra, al mismo tiempo debe realizarce un movimiento corto pendular.
2. Segun el 1er toque de la piedra con el disco , se determina el movimiento de la invension: ejm, si el brillo es hacia la izq y abajo , se debe inclinar la invension hacia el lado derecho y hacia arriba.
en medio de los toque no olvidar , humectar el disco con la solucion de oxido de cerio + H2O.
1. Inicio por bisel
sujecion de la piedra , con el indice y el pulgar.
el brillo se determina por un sonido grave, eso quiere decir que empata bien la faceta con el disco ( disco de estaño y plomo) , previamente rayado con el bisturi para permitir resultados optimos del brillado.
el oido es el que determina que esta pasando con la piedra, al mismo tiempo debe realizarce un movimiento corto pendular.
2. Segun el 1er toque de la piedra con el disco , se determina el movimiento de la invension: ejm, si el brillo es hacia la izq y abajo , se debe inclinar la invension hacia el lado derecho y hacia arriba.
en medio de los toque no olvidar , humectar el disco con la solucion de oxido de cerio + H2O.
TALLA DE PIEDRAS - NOV 13 / 07
FACETEO - ESCALONADA CUADRADA
PROCEDIMIENTO
1. Montar la piedra al baston - palillo
2. Acomodar el bisel a 90 grados de la piedra.
bisel: 3a parte de la altura total de piedra.
3. Debe estar paralelo uno de los lados de la piedra con los lados del baston , este debe ser apretado hasta que no giere el palillo.
4. El instrumento que nos colabora con la elaboracion de facetas de la piedra es la invension , este es un apoyo para cambiar el angulo de la piedra, este contiene unas perforaciones localizadas a lo largo de este, y posee un brazo , que es el apoyo y sostenimiento del baston paralela a la superficie de talla.
5. para relizar el bisel que es de 90 ºgrados localizamos la punta del palillo que se encuentra dentro del baston en el No 2 o 3 de la reflilla de la invension.
6. Marcar el lado de la piedra en el lacre de pegado con el cual se inicio a facetear.
7. Regla: contacto visual y concentracion absoluta con la piedra.
8. Desde la vista del tallador de plata de la pidra no se debe ver , ya que no nos permite una definicion completa de la angulacion de las facetas.
9. Una piedra con un angulo bajo en su bisel conlleva en el engaste el rompimiento de la piedra.
10. Luego de terminar el 1 er lado se prosigue a lso otras tres lados sin mover de ningun modo la invension.
11. Solo se trabaja con una hilera de orificion en caso de que la invension contenga 2 hileras de orificios.
12. Los angulos de las facetas se controlan con ayuda de gloniometro.
13. debe hacer un goteo moderado hacia el disco en la mesa de talla.
14. El angulo de la faceta principal es de 42 º grados No 15 - 16 de la reglilla.
15. En cada faceta debe cambiarse la posicion de la invension de acuerdo a la localizacion del faceteado.
16. El angulo de la contrafaceta 26º No 19 en la reglilla, esta debe ser de un toque suave, no tan ancha como la faceta principal.
PROCEDIMIENTO
1. Montar la piedra al baston - palillo
2. Acomodar el bisel a 90 grados de la piedra.
bisel: 3a parte de la altura total de piedra.
3. Debe estar paralelo uno de los lados de la piedra con los lados del baston , este debe ser apretado hasta que no giere el palillo.
4. El instrumento que nos colabora con la elaboracion de facetas de la piedra es la invension , este es un apoyo para cambiar el angulo de la piedra, este contiene unas perforaciones localizadas a lo largo de este, y posee un brazo , que es el apoyo y sostenimiento del baston paralela a la superficie de talla.
5. para relizar el bisel que es de 90 ºgrados localizamos la punta del palillo que se encuentra dentro del baston en el No 2 o 3 de la reflilla de la invension.
6. Marcar el lado de la piedra en el lacre de pegado con el cual se inicio a facetear.
7. Regla: contacto visual y concentracion absoluta con la piedra.
8. Desde la vista del tallador de plata de la pidra no se debe ver , ya que no nos permite una definicion completa de la angulacion de las facetas.
9. Una piedra con un angulo bajo en su bisel conlleva en el engaste el rompimiento de la piedra.
10. Luego de terminar el 1 er lado se prosigue a lso otras tres lados sin mover de ningun modo la invension.
11. Solo se trabaja con una hilera de orificion en caso de que la invension contenga 2 hileras de orificios.
12. Los angulos de las facetas se controlan con ayuda de gloniometro.
13. debe hacer un goteo moderado hacia el disco en la mesa de talla.
14. El angulo de la faceta principal es de 42 º grados No 15 - 16 de la reglilla.
15. En cada faceta debe cambiarse la posicion de la invension de acuerdo a la localizacion del faceteado.
16. El angulo de la contrafaceta 26º No 19 en la reglilla, esta debe ser de un toque suave, no tan ancha como la faceta principal.
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