Removing stones from scrap jewelry?

So I am just getting into the whole karat gold business and ws wondering how one would remove the stones from old broken rings and etc. without scratching or damaging the stone?

thx
-roxx

you need to very carefully bend the little fingers holding it down. Depending on the cut of stone the will be 4 or more.

Roxx said:

So I am just getting into the whole karat gold business and ws wondering how one would remove the stones from old broken rings and etc. without scratching or damaging the stone?

thx
-roxx

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I refined for a pawn shop that didn't remove the small stones, anything under about .2 carat in size. I used a flex shaft and a small abrasive disc to cut the prongs. Doing them by other means was too slow, because the amount of scrap submitted for refining was large----often yielding near 100 ounces of gold. I made more money on the removed diamonds than I did on the refining. They didn't want them returned.

You need not fear hurting a diamond with a grinding wheel of the type I described-----but softer stones can be harmed if you don't use care. For me, it was worth the risk to make stone removal a faster process.

I made a small glove box with a viewing window (piece of large diameter plastic pipe with a Lucite window) so I could catch the grindings that came from the stone removal process. No losses that way.

Harold

Why all this trouble ?
I simple dissolve the gold and the diamonds stays at the bottom. You can recover them after filtering.

Some stones won't stand up to the aqua regia. Pearls will definitely be attacked.

Wow great answers abound around here. I agree with Catfish's general idea that personal refining of Karat Gold isn't very lucrative, but if the best way to remove stones is to dissolve the gold around them it may be more economical to do the refining in-house just to recapture the stones.

So I guess I'm saving up for Hoke's book.

Is AR the best method of dissolving karat gold from around stones or would a reverse electrolysis process be better.

-roxx

AR is NOT the best method for karat gold since you have silver alloyed with your gold.

I would recommend karat cell.

After leaching with nitric (if 10K was present), I always used AR directly on most all karat gold. If anything was left over, I would inquart it and get it next time. RARELY was anything left over. Please note, however, that I was buying the karat gold I was processing. It was mine. I owned it. I could process it any way I wanted. I didn't have to get it all the first time, although I usually did. I personally think that direct AR is the best way to run karat gold or dental gold.

I agree that you must use Nitric prior AR. But I wouldn't call it direct Aqua Regia

GSP, you are using nitric acid with 10k gold and lower I suppose ? What if it is 14k-18k ? And do you use 35%-40% Nitric Acid ?

Thanks

With a mixed lot, 6K through 22K, I always first hit it with hot 50/50 nitric. It may or may not dissolve something. Then I pour it off, cover it with an excess of HCl, heat it up, and feed it with small increments of HNO3. When an addition of HNO3 produces no reaction, I know I'm finished. No urea needed. No evaporation needed. Why? - because I didn't use an excess of nitric. In most cases, all the karat gold is dissolved. If anything is left, I inquart this small amount. There will always be some trapped Au solution in the AgCl. This is easily recovered during the AgCl to Ag conversion.

Alright thanks.

Ok so i think I might be getting the idea behind this. The nitric acid bath will get rid of the silver , and the HCL and HNO3 combination dissolves the gold. At which point i will need a precipitant to recover the pure gold mud. I currently have just 2 questions:
1. Do I need to rinse and dry my material in between the nitric bath and the start of the AR process?

2. How will all these abrasive chemicals effect the quality of the stones
I wish to retrieve from the solutions? Both Diamonds and semi-precious stones.

(1) No. Just let everything settle and then pour off as much nitric as you can. Then, go to AR.

(2) No problems with diamonds. Some of the other stones can be affected. I don't have a list. Pearls are severely affected.

What about reverse electrolysis? If I built a karat cell would I be able to quickly recover the gold without harming the stones?

The diamonds are made from carbon so they are pretty rugged. Pearls are more of a organic and will be affected by chemicals of high oxidation i.e. Nitric, sulfuric, or any strong oxidizer. Just think of what happens when your skin is exposed, it organic.

Pearls

Contrary to popular belief, pearls hardly ever result from the intrusion of a grain of sand into an oyster's shell. Instead, a pearl forms when an irritant such as a wayward food particle becomes trapped in the mollusk. The animal senses the object and coats it with layers of aragonite ("ah-RAG-uh-nite") and conchiolin ( "KON-kee-uh-lin"). These two materials are the same substances the animal uses to build its shell.

In most pearls, the mineral aragonite is arranged in sheets of flat, six-sided crystals. Between each sheet, the mollusk secretes a very thin layer of the membrane-forming protein conchiolin. This composite material is called nacre ("NAY-ker") or mother-of-pearl. The crystalline structure of nacre reflects light in a unique way, giving so-called nacreous pearls their high luster. In contrast, some pearls are not nacreous and instead have a low-luster, porcelainlike surface. The needlelike crystals of aragonite in these pearls are arranged perpendicularly or at an angle to the surface of the pearl.

goldsilverpro said:

With a mixed lot, 6K through 22K, I always first hit it with hot 50/50 nitric. It may or may not dissolve something. Then I pour it off, cover it with an excess of HCl, heat it up, and feed it with small increments of HNO3. When an addition of HNO3 produces no reaction, I know I'm finished. No urea needed. No evaporation needed. Why? - because I didn't use an excess of nitric. In most cases, all the karat gold is dissolved. If anything is left, I inquart this small amount. There will always be some trapped Au solution in the AgCl. This is easily recovered during the AgCl to Ag conversion.

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This method seems like it goes against what I've been learning in Hoke's book.
Without the inquartation process and proper nitric acid digestion, wouldn't the AR digest all the base metals along with the gold..resulting in gold containing lots of contaminants?
And also, doesn't the formation of AgCl prevent the karat gold from dissolving in the first place?
Is there some sort of industrial method of refining gold without inquarting to 6k?

I just finished Hoke's book, so I still have a lot to learn
Hope you can clarify this~~ thanks in advance!

I use a small Ammonium and sodium Chloride electrolyte stripping cell. U.S. Patent 4895626.
The hook to hold the ring is made out of Titanium(anode) so is unaffected by the process,and the cathode is stainless steel.
I still only add enough electrolyte to cover the part of the ring that has stones.
I had some white gold rings with nice diamonds left ,the larger ones had been removed before me.,but the settings where to deep to pry out.
So I ran it in the cell for two or three hours,the stones drop out easily and I just put all the filtered cell slime straight into my next Inquartation .
Will work with any alloy and Ammonium and Sodium Chloride will only affect the most vulnerable of stones.

In refining and recovery sometimes we need to achieve slightly different things recovering valuable stones from karat scrap been one example thereof.
The procedure is the same as mine, you boil all the scrap in nitric in the hope it removes some of the base metals and silver if present followed by the AR to dissolve the metal from around the stones, in some cases all the gold will dissolve in others as you noted silver chloride will form a protective shell and stop it but hopefully enough metal dissolves to allow easy stone recovery.
This whole process is really a recovery rather than a refining process.

justinhcase- Thanks for the patent number and new technique. That method seems to be the one that gives the least hassle in removing stones. I think I'll have to do more research on it though. Whenever I read ammonia, I want to make sure it's not going to become a problem with my metals :shock:

nickvc said:

This whole process is really a recovery rather than a refining process.

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This is what I was leaning towards. Which got me wondering about the process..
1. Leave the jewelry with stones in AR long enough until the stones can be removed. 2. Once stones are gone, clean the gold piece and Inquart and proceed as usual.
If the AR digests the jewelry enough for the stones to fall out, am I correct in thinking that the AR solution will now contain traces of gold along with other base metals? What am I supposed to do with this "contaminated" AR solution?

I was concerned that if I proceed to precipitating the gold, all the other base metals drop out as well, therefore leaving me with impure and brittle gold..
Or is this "contaminated" AR solution something that goes into the stock pot and recovered later.

Thanks for the replies ^^
Still trying to learn all the methods so I can avoid trouble down the road
Cheers

That's one of the Shor patents.