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 Post subject: one more black diamond question
PostPosted: Wed Mar 06, 2013 2:02 pm 
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Joined: Wed Mar 06, 2013 1:40 am
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Location: Portland, OR
Okay this refers to the diamond I previously posted about, but it's more of a specific identification question.

I have this stone, which my mother who was an amateur gem enthusiast identified as a black diamond... I don't know what all testing methods she might have used to do that. I used an electronic diamond tester which did read that it is a diamond.

Question: Does that mean I can trust that it is? Or are those results easily erroneous? Is there another way I should confirm it? I currently know almost nothing about gemology (obviously) :)

(An acquaintance wants to buy it, however I don't think I will allow her to pay anything for it after learning more about how truly little value they have. BUT that being said, it occurred to me that I don't really know it's a diamond if that test isn't accurate, and I'd feel terrible saying it's a diamond if there's a good chance it's not.)

Once I get over this little black diamond issue, I'll be able to relax and enjoy exploring what else is in my little mystery cache of gems. Thanks for the help.


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 Post subject: Re: one more black diamond question
PostPosted: Thu Mar 07, 2013 1:54 am 
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Location: San Francisco
A diamond tester should test black diamonds as diamonds with accuracy.
Have you tested it with something you KNOW is a diamond and something you know is not a diamond to check it?


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 Post subject: Re: one more black diamond question
PostPosted: Thu Mar 07, 2013 3:17 am 
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Yes. Tested it against a couple known diamonds and a few other non-diamonds, got consistent results. Thank you, that is reassuring and very helpful.


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 Post subject: Re: one more black diamond question
PostPosted: Fri Mar 15, 2013 2:29 pm 
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I have one more comment since I too purchased a number of those type parcels several years ago. I also found a black diamond, but double check its quality with a loupe. Mine had numerous tiny chips around the girdle. Probably from bouncing around in the container and then the bag with all the other stones. So its value is certainly almost nil because it would not be worth the cost of having it recut. Still, interesting to have all the same.


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 Post subject: Re: one more black diamond question
PostPosted: Fri Mar 15, 2013 11:01 pm 
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Location: Portland, OR
Thanks! I've been scrutinizing it. Everyone's insight is appreciated.


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 Post subject: Re: one more black diamond question
PostPosted: Thu Mar 21, 2013 5:42 pm 
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Joined: Thu Oct 11, 2012 6:29 pm
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I heard a tidbit at the last faceting guild meeting that you might be interested in.

Black/brown opaque diamonds, aka bort, or industrial diamonds, have great use as abrasives. Produced by the ton, they're ground to powder and seived to provide various grit sizes, from coarse 80 grit to super-fine polishing 100,000 grit, for example.

Cutters and polishers of gemstones have long relied upon this material to facet their stones, as it's cheap and cuts fast. However, recent improvements in industrial diamond crystal synthesis have rendered the natural material obsolete. Seiving doesn't eliminate the over-size particles that can slip thru a seive - imagine a 2x4, it could fit thru a 5' seive, even though it's 8' long in the other dimension! Oversize particles like that play havoc with polishing. The diamonds grown in the lab, however, are grown to specific sizes, and are much more reliably sized.

So the diamond producers now find themselves with unwanted tons of bort, which has become little more than industrial waste that has to be gotten rid of.

Enter the marketers. Opaque black diamonds are now rare and cool!

Problem solved.


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