# Stone Removal



## JOEYL (Feb 24, 2011)

3 questions for the forum, all somewhat related:

How do refiners do stone removal on scrap jewelery ? Nitric Boil or HCL Boil and the diamonds come loose? Or does the material go direct to Aqua Regia?

Also curious are diamonds that go through a melt and are in the borax get ruined in any way ?

Is there a standard price list for misc diamonds with grading descriptions?

Thanks in advance, I know there must be a few people educated on diamonds.


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## 4metals (Feb 24, 2011)

I can only answer your first 2 questions. 

Aqua regia is used to dissolve away the gold and loosen the stones. All that remains will be some silver chloride encrusted pieces of gold and silver chloride and the stones. dissolve the silver chloride and you have the stones. 

Diamonds that have been melted and fluxed off in the borax can be removed by dissolving the borax in boiling hot water, it is slow and the borax will soften and begin to dissolve. When the water gets saturated with borax change it out and boil it again. When no more dissolves you are left with a fraction of the flux volume you started with and the gold remaining in the slag can be digested out and the stones can be picked out. Personally I feel this is a lot of work for some small diamonds but that's my opinion. 

The 3rd question is better answered by a diamond guy, I use the pawnbrokers guide for diamond grading and pricing.


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## Lou (Feb 25, 2011)

Get the Rapaport diamond buyer's guide, it will help. Stones are graded on cut, clarity, color, and of course, carat (easy to remember). Generally speaking, the melee diamonds aren't worth much until you've accumulated several carat's worth.


Diamonds burn, so it's best to chemically remove them. Cubic zirconia is highly refractory and can't be oxidized (burn) like diamond, so they're persistent and often float to the top of the melt. Usually one can get them trapped in the borax if one adds a few pieces of broken pyrex to thicken up the flux to the point where it can be held back with a quartz fork and the alloy poured out from under it.

Many refiners use HF to frost the fake diamonds (CZ) from the real ones which are unaffected. This works quite well if one is in a high throughput environment where individually testing each stone's conductivity would be a lengthy endeavor.

Lou


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## chawimac (Sep 29, 2011)

"Many refiners use HF to frost the fake diamonds (CZ) from the real ones which are unaffected."

Does anyone know what HF stands for?


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## Harold_V (Sep 29, 2011)

chawimac said:


> Does anyone know what HF stands for?


Hydrofluoric acid, which should be avoided by the home refiner. It is extremely hazardous to one's health. As little as 25 square inches of skin exposed can be lethal. 

Harold


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## MysticColby (Oct 15, 2011)

Harold_V said:


> chawimac said:
> 
> 
> > Does anyone know what HF stands for?
> ...



It was featured in Saw 6 ^_^
At the time, I wondered if the people in that room would be affected by fumes or such


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