High Pressure-High Temperature (HPHT) diamonds

[SCARLETTE]

How do the experts here feel about HPHT-treated diamonds to change the color of the diamond. I came across a diamond with this treatment and wondered if it is similar to clarity-enhanced techniques and if it "harms" the structural integrity of the stone in any way.

 

[treasurehunter]

It does not harm the structural integrity of the stone in any way we are talking about atomic sized irregularity in the crystal structure by using high heat they remove that defect which removes from the stone a brown colour,
There is nothing wrong with HPHT if it is disclosed and you know it exists and you are paying the price you would for the stone if it were its original colour, probably brown .

 

[leoshraeder]

HPHT can "harm" the structural integrity of the stone but this should be reflected in the clarity grade of the stone. High heat can cause inclusions like feathers to extend during the treatment process.

 

[luvmysparklies]

Not an expert, but I have been told by a jeweler that this is a corrosive process and you take a chance of the diamond breaking during the treatment. As I was told, once the diamond undergoes the treatment, it requires re-polishing because the stone gets etched in the process. If the diamond survives the treatment and the treatment is openly disclosed and price is reflective, then you should be good. This process is different from clarity enhancing such as laser drilling and fracture filling and I don't think with this process, you'd have to take any special precautions with the diamond like some clarity enhanced stones.

I saw a honker of a diamond on JBEG that looks just beautiful and has been HPHT treated to bring it to a J. The accompanying report indicates everything is fine with it structurally as well.

 

[periwinklegirl]

I have two lovely fcd pinks that were HTHP treated.

 

[treasurehunter]

Usually they HPHT very high clarity diamonds , not ones which that will have structural problems due to the heating.

 

[Paul-Antwerp]

In general, the wholesale-value of a HPHT-treated stone is about 60 to 70% of natural untreated.

Live long,

 

[denverappraiser]

As an owner, no you are not at risk of structural problems from the HPHT process. During the processing, certain inclusions, especially other minerals, can be damaged and this can harm or even destroy the stone. Obviously the people doing the treating are sensitive to this. The point of the treatment is to make a stone that's MORE marketable, not less. It's one of the reasons that stones sent in for HPHT treatment tend to be high clarity. The other is that not every diamond CAN be treated. Actually it's rather few. Under 2% are of the correct type where it's even an option. I'm told that these tend to be high clarity for geologic reasons but I've never looked into it. Perhaps there are others here who can add more.

 

[Karl_K]

Here is an article from 2011 on hpht that covers the basics:
http://www.jckonline.com/2011/05/21/abcs-hpht

 

[Karl_K]

This one has more info:
http://www.israelidiamond.co.il/English/news.aspx?boneId=2523&objid=7604

 

[Andelain]

From all I've read, I wouldn't hesitate to buy a HPHT treated stone if....

I liked the stone,
treatment was disclosed,
it was priced accordingly.

I doubt I'd risk a stone I already have with that treatment.

 

[diamondseeker2006]

I do find this a highly interesting topic. While I would never consider a clarity enhanced diamond, I am thinking I could consider these.

Where can they be bought? Can one of the regular vendors access them?

 

[denverappraiser]

They're sold through the usual sorts of channels to untreated diamonds. They're a lot harder to come by, so you can't be particularly picky in other ways, and a lot of dealers don't stock them because they don't sell all that well, but your favorite jeweler can almost certainly get you one if you ask.

 

[SCARLETTE]

Not an expert, but I have been told by a jeweler that this is a corrosive process and you take a chance of the diamond breaking during the treatment. As I was told, once the diamond undergoes the treatment, it requires re-polishing because the stone gets etched in the process. If the diamond survives the treatment and the treatment is openly disclosed and price is reflective, then you should be good. This process is different from clarity enhancing such as laser drilling and fracture filling and I don't think with this process, you'd have to take any special precautions with the diamond like some clarity enhanced stones.

I saw a honker of a diamond on JBEG that looks just beautiful and has been HPHT treated to bring it to a J. The accompanying report indicates everything is fine with it structurally as well.

That's exactly what sparked my interest. After reading the comments here and the links to a couple of the articles, I don't think I would be adverse to buying a HPHT treated diamond. I just need to make sure that it's my "final" upgrade because I think the resell/trade-in market for it would be abysmal.

 

[diamondseeker2006]

Thanks, Neil!

And I agree, Scarlette, it would have to be something that you wouldn't want to sell later, unless they catch on here, of course! I think it is a nice way to get a larger OEC in a higher color.