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- Feb 25, 2007
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When I was refining, buying chemicals wasn't much of an issue. I purchased all of my acids. Nitric, purchased in 55 gallon lots, cost just over $200 per drum. I owned my own stainless 55 gallon drum, so I exchanged for a full one.
The ratio for aqua regia is not commonly agreed upon. Many say 3 parts HCl, 1 part nitric. I used 4 parts HCl, 1 part nitric. I also used water, but that is an option you may or may not use. It should extend the use of the acid, although it will slow its pace a little.
My reasoning behind using a 4:1 mix?
Excess HCl does no harm. By providing a little excess, you insure consuming your nitric, instead of running short and assuming you have exhausted the nitric.
Mix AR only as it is needed. It gasses, with terribly corrosive vapors. If you stopper a vessel tightly, you risk breaking from internal pressure.
Harold
The ratio for aqua regia is not commonly agreed upon. Many say 3 parts HCl, 1 part nitric. I used 4 parts HCl, 1 part nitric. I also used water, but that is an option you may or may not use. It should extend the use of the acid, although it will slow its pace a little.
My reasoning behind using a 4:1 mix?
Excess HCl does no harm. By providing a little excess, you insure consuming your nitric, instead of running short and assuming you have exhausted the nitric.
Mix AR only as it is needed. It gasses, with terribly corrosive vapors. If you stopper a vessel tightly, you risk breaking from internal pressure.
Harold
Since I am getting so much from this forum.
I might as well give you a trade secret
To remove stones you use carbide disc
It eats the beads and the claws and nothing happens to the diamond
If you have other stones that are softer than diamonds then they will get scathed.
I might as well give you a trade secret
To remove stones you use carbide disc
It eats the beads and the claws and nothing happens to the diamond
If you have other stones that are softer than diamonds then they will get scathed.
qst42know
Well-known member
I have never done more than a few stones at a time but I have had good luck with the rod of an ice pick pulled from the handle and sharpened to a tiny jewelers sized chisel point. Sometimes a push is all that is needed or a light tap with a small hammer will cut the end of the stubborn prongs off. A wooden woodworkers clamp will hold all sorts of odd shaped pieces while you work on them. It goes much faster than it sounds.
A third generation jeweler friend once told me that, when removed, 90% of the diamonds under 1 carat, were damaged. I know zero about diamonds so, I'm just repeating his words.
qst42know
Well-known member
I suspect it is the skilled jeweler who hides cheap flawed diamonds beneath the prong heads. I would think any gold alloy too ductile to damage a diamond. Opposing prongs are merely squeezed tight enough to grip the stone by pliers, peening, or by drawing a burr.
Is a diamond really that brittle or was the stone already cracked or otherwise flawed?
Is a diamond really that brittle or was the stone already cracked or otherwise flawed?
- Joined
- Feb 25, 2007
- Messages
- 8,360
I processed for a pawn shop that removed all substantial stones, but left anything smaller than roughly 20 points. I used to remove them regularly, and sold them for additional profit. Prong set diamonds are easy to remove, but bead set stones are much harder, due to the small exposed beads that hold the diamond. The use of an abrasive parting wheel and a flex shaft, working in a "glove box" to capture the diamonds and wasted values made removal easy. I made more money on the diamonds than I did on the refining. Diamonds so removed are not damaged. Stones of less value are, those that are not as hard as diamond.goldsilverpro said:
I'll share something with you you may find hard to believe.
I screened polishing wastes after incineration, and recovered a fair number of diamonds in the process. What surprised me was when I ran the two 55 gallon drums of polishing wastes that I had accumulated. They were processed with AR for extraction, but I was aware that total extraction was not to be expected. I ran them in my agitation tank with cyanide, but in order to do so, they had to be run through the ball mill, where the pH was changed to basic. I introduced hydrated lime along with the wastes, shifting the pH to roughly 10. The material, upon being discharged from the ball mill, was classified by a fine screen. To my surprise, I recovered something like 100 small diamonds that had been through the ball mill---all without damage. Keep in mind, the ball mill had steel balls up to 2" diameter, and it ran at the proper speed, where the balls were dropped from the apex of the top curve, crashing down on the contents of the mill.
Diamonds are very tough and can take some serious abuse. None of the man made, or naturally occurring abrasives harm diamond in the short term. They are used routinely for dressing grinding wheels made of silicon carbide, which is harder than aluminum oxide by a long shot.
Harold
edit: corrected typo
Hi Folks
Thanks for your interesting thoughts
I have been a setter for a long time and I have removed many stones.
When a diamond is of good quality and the cut is of good proportion you can just poke a sharp object and give it a wack from the back of the piece and it will come of.
But if the stone is set very well and the claws are holding the stone well then doing this can brake the stone.
After a bit of experience you get the feel of the trade and things move along rapidly
Thanks for your interesting thoughts
I have been a setter for a long time and I have removed many stones.
When a diamond is of good quality and the cut is of good proportion you can just poke a sharp object and give it a wack from the back of the piece and it will come of.
But if the stone is set very well and the claws are holding the stone well then doing this can brake the stone.
After a bit of experience you get the feel of the trade and things move along rapidly
