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What Is The Most Efficient And Cost Effective Way Of Sorting High Volume Melees?

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What is the best way to sort melee diamonds of all colors, clarity and sizes? For example if I extract diamonds (breakouts) using the aqua regia method of refining. My question is once I sort all the whitish-appearing stones including diamonds, cubic zirconium, moissanite, from the batch what is the best way to extract only diamonds from a parcel that may have 2500-5000 carats in total, without the use of optical or thermal identification methods?

 

P.S. I have heard of a chemical solution that separates moissanite: based on density. Is this the best option?

 

I am looking for the most efficient and cost effective way of sorting high volume melees that will have (diamonds, CZ, moissanite) in the batch. Your thoughts....

 

Regards Ron

Edited by ronk15a

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The specific gravity of moissanite is lower than that of diamond & CZ and it will float in methylene iodide (SG = 3.33) while diamond and zircon will sink in it.

 

SPECIFIC GRAVITY

NATURAL & SYNTHETIC MOISSANITE:3.21-3.22

DIAMOND: 3.52

ZIRCON:4.73

Edited by ronk15a

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It is also very toxic, and :unsure: not very happy about that....Please advise?

Edited by ronk15a

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High density liquids are dangerous and a pain to use - yes, you would only have CZ and diamond since they sink in CH2I2, but given the relative frequency of CZ and moissanite I don't think it's going to be worth the risk and expense. BTW - the density of zircon (ZrSiO4) is one thing; CZ (cubic form of ZrO2) is another; the density of CZ is even higher than that of zircon, at about 5.5-6.0 (depending on dopants), and no, as far as I know there are no commonly available liquids with a density above that of MI.

 

On the other hand - I don't know to what extent it would work for CZ and moissanite, but diamonds are industrially separated from kimberlite and other rocks through the use of greased tables which are then washed out with water. The diamonds stick to the grease, the rocks don't. Depending on the quantity of stuff you really have to go through, it may be worth building a small separation table (same principle as a gold separation table, except that there is grease on it).

 

Re: your latest post: gimme a minute! I'm typing!

Edited by davidelevi

Davide - Specialised Consumer Information and Assistance,
Diamonds by Lauren (http://www.diamondsbylauren.com)
davide@diamondsbylauren.com

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Never say never - just found out about the Clerici solution, but since it's a mixture of two salts of thallium, I think it's best left alone. It's corrosive and highly poisonous. But it has a density of 4.25 - 5 (depending on temperature), so it would separate diamond from CZ.


Davide - Specialised Consumer Information and Assistance,
Diamonds by Lauren (http://www.diamondsbylauren.com)
davide@diamondsbylauren.com

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A common strategy I've heard for the pawn shops is to heat the whole lot in a kiln and then quench it in water. The CZ's will be destroyed and the diamonds will survive. You still have to pick them out but a low wage worker can actually do it fairly quickly since crackled CZ's look rather obviously different from diamonds. Perhaps the old mining technique of using a grease table would be useful as well. Diamonds stick, CZ's don't. It doesn't seem out of the question to invent a tool for this.

 

Moissanite melee is pretty unusual by the way. Depending on the source of the breakouts, I doubt you'll encounter any. Zircon even more so. I doubt you'll even encounter it. White sapphire is out there and should be considered in your separation but the vast majority of your non-diamond is going to be CZ.

 

As a completely random idea, you might be able to do it pretty well with a gold pan and a bit of practice.

Edited by denverappraiser

Neil Beaty

GG(GIA) ICGA(AGS) NAJA

 

There's never a crowd when you go that extra mile.

Professional Appraisals in Denver

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Just my thought: Almost all options seem rather poor. The MI option is costly, and toxic, and only separates moissanite from other sub-types, and based on Neil's theory (which I tend to agree with) there will not be many moissanite stones in the batch.

 

The Clerici solution sounds really really toxic and NOT worth the exposure or risk! Grease table sound dirty, cumbersome, and annoying….

 

Kiln sounds descent, at what temperature to they run?

 

"Neil" Gold Pan- Is this a JOKE?

 

In regards to the Kiln: Would you happened to know the exact technique, where to learn it, or if there happens to be any on-line tutorials for it?

 

FWIW: The melee will range from .0025 of a point to .30 points in size.

 

Regards R.K.
 

Edited by ronk15a

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Gold panning is fundamentally a SG separation and CZ is nearly double diamond.  I must admit I've never tried it with diamonds but that seems like enough that it just might work. 

 

No, I don't know any tutorials, and I've never personally done it so I can't say I'm endorsing this, it just seems like it would work.  I've never needed to do what you're doing.  Practice with a few known CZs and see what it takes to crackle them.  I would guess 700 degrees is probably enough. 

 

In the case of 0.30's, or even the 0.15s  I'd pick them out individually.  2000 carats of thirty pointers is a LOT of money unless they're really bad stones and it wouldn't be that hard to just do it by hand.  2000 carats of 0.0025s, on the other hand, would be a serious pain to separate that way.   Actually that's another clue for your sort.  I don't recall ever seeing 0.0025ct CZs at all.  I suspect that it doesn't justify the cost to manufacture them and they would just as soon use diamond since the cost of the finished stone is mostly in the labor anyway.

 

I actually DID have need to do a big separation once.  A charity had a contest where they filled up a fishbowl with CZs and dropped in one diamond of the same size.  You could buy a ticket to pick one stone out and I would examine it and tell them if it was real.  No one won the price so, at the end of the day, it was necessary to pick out the real one both to show people that it was there and to give it back to the store to sell.  


Neil Beaty

GG(GIA) ICGA(AGS) NAJA

 

There's never a crowd when you go that extra mile.

Professional Appraisals in Denver

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Gold panning is fundamentally a SG separation and CZ is nearly double diamond.  I must admit I've never tried it with diamonds but that seems like enough that it just might work. 

 

SOUNDS LIKE A POOR OPTION: WITH MANY ERRORS BOUND TO OCCUR

 

No, I don't know any tutorials, and I've never personally done it so I can't say I'm endorsing this, it just seems like it would work.  I've never needed to do what you're doing.  Practice with a few known CZs and see what it takes to crackle them.  I would guess 700 degrees is probably enough. 

 

IMO: NOT WORTH THE RISK OR CRACKING DIAMONDS IN THE PROCESS

 

In the case of 0.30's, or even the 0.15s  I'd pick them out individually.  2000 carats of thirty pointers is a LOT of money unless they're really bad stones and it wouldn't be that hard to just do it by hand.  2000 carats of 0.0025s, on the other hand, would be a serious pain to separate that way.   Actually that's another clue for your sort.  I don't recall ever seeing 0.0025ct CZs at all.  I suspect that it doesn't justify the cost to manufacture them and they would just as soon use diamond since the cost of the finished stone is mostly in the labor anyway.

 

IF IT WAS ONLY 5,10,15,20,25,30 I AGREE HAND/OPTICS - NO QUESTION! BUT VERY VERY SMALL STONES ARE MY MAIN CONCERN .25 .5 .75 1PT .3 ETC...

 

I actually DID have need to do a big separation once.  A charity had a contest where they filled up a fishbowl with CZs and dropped in one diamond of the same size.  You could buy a ticket to pick one stone out and I would examine it and tell them if it was real.  No one won the price so, at the end of the day, it was necessary to pick out the real one both to show people that it was there and to give it back to the store to sell.  

 

HAHAHAHHA - THATS FUNNY! -I LIKE THAT "PLOY" U EVER HERE OF THE ONE WHERE THE STORE GIVES A FREE DIAMOND RING TO EVERYONE PERSON IF IT SNOWS ON CHRISTMAS! STORE/SALES GIMIC (GOOGLE IT)

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OK I’m in the finishing stages of my melee sorting project....Just separated, and cleaned a huge batch of stones. What an f***in pain in the ass. I’m working with roughly 2000 carats. I need to now sort the stones by mineral. (Diamond/CZ) then: size, color and clarity. I re-read everything you guys said: Thought about something else. Would fluorescence work to separate diamond from cubic zircon quickly? Ad least I know stones with fluorescence must be diamonds....the rest I will have to do optically. Your thoughts?
 
Regards R.K.

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I've nothing useful to contribute but this thread is most fascinating!

 

I grew up with an Asian fairytale where the heroine had to sort beans before she could go to the ball! Hehe you remind me of that!

 

Is there any chance you can post a picture of what you need to sort? Pretty please?

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I've never tried it with melee but bigger stones look rather different if you immerse the parcel in water. Baby oil or some other liquid with a higher RI would probably be even better.


Neil Beaty

GG(GIA) ICGA(AGS) NAJA

 

There's never a crowd when you go that extra mile.

Professional Appraisals in Denver

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Fluorescence would probably get you 10-15% of your diamond load, so it's a worthwhile exercise (100 fewer carats - 2000 fewer stones? I'm guessing 50/50 CZ and 5 pointers average). It still leaves a lot, but better than nothing.

 

Bear in mind that CZ and moissanite (and some rare earth garnets - YAG/GGG) are not necessarily inert, but they all tend to have weak orange fluoro. As far as I know, no blue, which helps, since 99%+ of diamond fluoro is blue.


Davide - Specialised Consumer Information and Assistance,
Diamonds by Lauren (http://www.diamondsbylauren.com)
davide@diamondsbylauren.com

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Hey Davide! That sounds awesome! -Leave me your number in PM. This week I'm unfortunately very busy, however next time you’re in the states I would definitely take you up on your offer.
 
Ron K.

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Quote

What is the best way to sort melee diamonds of all colors, clarity and sizes? For example if I extract diamonds (breakouts) using the aqua regia method of refining. My question is once I sort all the whitish-appearing stones including diamonds, cubic zirconium, moissanite, from the batch what is the best way to extract only diamonds from a parcel that may have 2500-5000 carats in total, without the use of optical or thermal identification methods?

Dear Ron,
I was interested in your post "What is the best way to sort melee diamonds of all colors, clarity and sizes?"
About this problem, I accidentally found out  on the Internet in March of this year, when I was developing  design of the Device for freezing CZ's without harmful hydrofluoric acid (see my eBay http://www.ebay.com/itm/142387010973). According to your post, you sort the gems obtained as a result of dissolution of jewelry in Aqua Regia with subsequent treatment of gems with hydrofluoric acid. I am also familiar with this process very well (see my eBay http://www.ebay.com/itm/131919322542).
Conceptually, I have already decided the problem of sorting CZ's from diamond melee. This is a simple desktop Device, where the water separates stones. It  works and sorts diamonds from CZ's by 100%. According to your message, you want to separate 2500 carats at a time. To do this, you need to design and test the Device with batch of 500 g of stones. If diamond bulk density is approximately 2 g /cc, the loading should be approx. 1 cup. Compare, now I'm experimenting with one teaspoon. In addition,  about a problem with Zircon - ZrSiO4 (d = 4.73 g / cc) and Moissanite - (d = 3.21-3.22 g / cc), I learned only from the text of your post.
Thus, for scaling of the process,  it is are necessary to make experiments. However, I do not have and will not have enough material without your participation in the project.
About me: I am a researcher and I have been engaged in design of chemical and hydromechanical processes for many years. I'm PhD of Chemical Engineering. If you wish, I show you my Diplomas, Scientific Articles, and Patents. For the last 7 years, I have been developing and selling desktop devices for extracting precious metals by non-professionals in rooms that do not have fume hoods (see my eBay).

Serge

Device total - 1.jpg

Edited by Viy
refinement

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