Diamond Boiling - What are the risks?

[TonisFan]

My fiance inherited a stone from her Great grandfather. We want to have this stone certified by either sending it to GIA or travel to Antwerp and deliver the stone to HRD.
HRD got a condition that all stones that they certify shall go through the process of being boiled in sulfuric acid and potassium sulfate.

I am aware that there are some risks in doing so, especially with larger, older stones. All diamonds should handle acid, except for boric acid at 700Celsius+ after which the diamond will start to 'dissolve'

I have heard of one stone that turned smokey grey, or that is, the table of the stone got 'smoked' or turned hazy to a degree that the diamond tester-tip made a trace metal mark, you could see that some copper was left on the table.
The stone was unharmed in any way apart from this, and the owner said that he thought it was possible to just polish the stone to bring it back to it's original beauty.

However that would have to be done before the stone could be certified, and then boiled again.
A trip to Antwerp from our country will be quite pricey, however it's possible to get an express service that would make it possible for us to take care of all buisness in one trip - unless the stone is burnt and have to be repolished.

Is anyone able to tell me exactly what the risks involed with diamond boiling are?
Thanks in advance

 

[MollyMalone]

I hope HRD isn't expecting you yourself to do this -- rather, you are asking the question because HRD has advised you their lab will do the procedure before grading the stone? (Does the inherited stone have a "bruted" girdle?)

If HRD is going to handle the boiling (and assuming it will be just the "regular" method, not a protracted heavy duty one), I'd be comfortable with them doing it, even if they aren't offering you an absolute guarantee that it will have no impact on the stone. My late father-in-law, who was " in the trade" here in NYC, had assembled a master set of diamonds for color grading which GIA had certified/registered. That was quite an investment on his part, in terms of both money & time, because GIA won't give its blessing to a set of random stones in the respective color grade categories; in addition to having been first graded by GIA, the diamonds in a set submitted for GIA's approval as a master set have to fall within other, strict parameters.

In order to preserve the professional value of his investment, he would periodically boil the diamonds in his master set. So far as I know, nothing adverse ever happened -- and I'd be willing to bet that HRD's lab has performed this far more frequently through the years than my father-law's total number of times.

 

[flyingpig]

http://www.gia.edu/gems-gemology/spring-2007-serenity-coated-colored-diamonds-shen

http://www.gia.edu/gems-gemology/summer-1989-diamond-filling-koivula

These are articles from GIA.
It looks like a common method to clean master stones, although certain diamond enhancement can be removed/damaged by sulfuric acid.

Interesting topic. I hope a trade member provides you with an expert answer

 

[Paul-Antwerp]

Hello,

It would surprise me if HRD would take care of the boiling on a customer's behalf, but I could be wrong. Still, that is not a problem as there are sufficient boiling-services in the Antwerp diamond-area, and the process generally takes only an hour with minimal cost. Beware though of jewish holidays, as most of these services close during such periods, like for instance Pesach at the end of April this year.

Generally, I see little risk for damage in the professionally executed boiling-process. If such thing occurs, it is generally because of a treatment being reversed, cases like glets-filling or even some undisclosed 'trick' to temporarily improve color-appearance. Other examples were 'presumed' diamonds which turned out to be some kind of diamond-simulant.

Live long,

 

[MollyMalone]

Such useful info for the OP (and the rest of us), Paul -- thank you!

Do you see a meaningful advantage in having HRD do the grading of the stone, which the OP would personally hand-carry to Antwerp, vs. the less costly alternative of shipping the diamond off to a GIA lab?

 

[Paul-Antwerp]

Good question, Molly, although I do not know whether the GIA-alternative is less costly.

In essence, your question whether there is an advantage for HRD over GIA or vice-versa highly depends upon the motivation of the OP.

That stone remains the same, whether without report or with. Is the aim to establish that it is a natural diamond, then both labs are equal in quality.

If the aim is to sell it, based upon the lab-report, it highly depends upon whom one aims to sell it to. In theory, a good GIA-report could then be more valuable, but given that this is supposed to be an old stone, that extra trade-value of a GIA report quickly evaporates.

Live long,