Questions about black diamonds

[Nashville]

What are the most common treatments associated with black diamonds? What should I be avoiding? Will any of these treatment affect long term durability of the stone?

Say I want to buy a parcel of black diamonds. Should I be looking for certified stones? Would it be wise to pay for a GIA cert, or is "in house" sufficient (this is what Leibish and Co. is offering on theirs)

I'm finding mostly only rounds, but I think a baguette halo (something like what is shown in the picture, but with and oval and without the double halo and smaller airline) would be really special. How much trouble is it going to be finding black diamond baguettes and if it's impossible, where can I locate rough material for cutting?

I know a lot of lapidaries choose to not work with rough they haven't sourced, so how likely is it I will find someone to source and cut rough black diamond, and will it be ridiculous price wise?

Thanks in advance!

 

[Diamond Explorer]

To my knowledge, most black diamonds are irradiated to achieve their deep color. This treatment is usually permanent and doesn't affect the durability. Smaller diamonds in a parcel would probably not be lab certified, as small diamonds, no matter what color, do not receive GIA certs. You will have to trust your source or have the goods independently appraised.

Finding small black baguette diamonds is no easy feat, but to try and source your own rough and have them polished is essentially impossible due to the nature of the rough diamond trading and polishing business. I think your only choice is to search for the polished diamonds directly, and you may need to contract the designer you are having make the ring to source the black diamonds for you. They have access to suppliers that do not sell directly to the public and could give you a greater chance of finding what you are looking for.

 

[Tom Gelb]

What are the most common treatments associated with black diamonds? What should I be avoiding? Will any of these treatment affect long term durability of the stone?

Say I want to buy a parcel of black diamonds. Should I be looking for certified stones? Would it be wise to pay for a GIA cert, or is "in house" sufficient (this is what Leibish and Co. is offering on theirs)

The two most common treatments for black diamonds are irradiation and heat treatment. The irradiation treatment is a relatively high dose of radiation that makes the diamond such a dark green to make it appear opaque. Only with a high powered light and sometimes even a microscope can one see the green. Unfortunately this sometimes leads to residual radioactivity emanating from the stone. My opinion is to avoid this treatment for that reason.

My understanding of the heat treatment is that the original diamonds are usually highly included with feathers and pinpoints. When the diamond is heated graphite forms along the feathers and surrounds the pinpoints to create a black color throughout the diamond. Does the effect durability? I am unsure if it is less stable after treatment than it was before, but the original diamonds are usually very included to begin with and thus there may be a durability issue. It is unclear to me whether the treatment makes it worse. This is also true of naturally colored black diamonds, they are generally highly included since it is the inclusions that create the color.

In terms of certification I would say it is necessary if one prefers the diamonds to be of natural origin. I will admit that I am biased, but an in-house report always makes me nervous.

Good luck

 

[Garry H (Cut Nut)]

Very dark sapphires are the best way to go.

Almost all small blacks are irradiated to very very dark green.

A lot of +1ct are low clarity with a lot of carbonized open gletz that go very dark on baking in an oven. These are fragile.

 

[denverappraiser]

With stones like you're discussing, a GIA grading report on each is likely to cost more than the stones themselves, especially if you're not fishing for natural color. Few customers are going to be intrested in that so few dealers will have already had the inspections done in advance. GIA will look at any stone that anyone is willing to pay them to look at but you will probably have to get the pedigree done yourself if you want and be prepared to spend quite a bit on it if you decide it's imporant.

 

[Nashville]

With stones like you're discussing, a GIA grading report on each is likely to cost more than the stones themselves, especially if you're not fishing for natural color. Few customers are going to be intrested in that so few dealers will have already had the inspections done in advance. GIA will look at any stone that anyone is willing to pay them to look at but you will probably have to get the pedigree done yourself if you want and be prepared to spend quite a bit on it if you decide it's imporant.

Thanks, maybe it was wishful thinking hoping that I could GIA certs on melee. I'd really prefer an all natural ring.

 

[Nashville]

Very dark sapphires are the best way to go.

Almost all small blacks are irradiated to very very dark green.

A lot of +1ct are low clarity with a lot of carbonized open gletz that go very dark on baking in an oven. These are fragile.

So maybe natural blue-black sapphires?

 

[Nashville]

Thank you so much for this information, it's been very enlightening to say the least!

I didn't think finding all natural black diamonds would be so tricky! I know I'm not going to want radiated, colored, heated stones, so I might have to go back to the drawing board, or examine sapphire/spinel options.

I truly thank you all for your time and knowledge!

 

[Garry H (Cut Nut)]

No one will ever be able to polish natural black baguettes and if they did you would break one every day.
The treated irradiated are safe and sound, no residual radiation or problems. But still not much chance of fancy shapes.

 

[Nashville]

No one will ever be able to polish natural black baguettes and if they did you would break one every day.
The treated irradiated are safe and sound, no residual radiation or problems. But still not much chance of fancy shapes.

Thanks so much, this is good to know.

 

[Tom Gelb]

Hello Gary,

I do not want to nitpick, but I have personally detected levels of radiation well above background on a number of irradiated black diamonds. It was certainly a small percentage, but they do exist. I am not a doctor, and have no knowledge if the radioactivity is dangerous, but I would advise anyone who is going to purchase these items to at least have them checked with a geiger counter.

Good luck