Appraisal vs Lab Report regarding heat treatment

[widget]

I know that a report from one of the big labs is best, but:

Can a reputable accredited appraiser pretty accurately determine if a ruby/sapphire has undergone heat treatment?....

Thanks!
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[bar01]

Date: 4/14/2006 9:45:06 AM
Author:widget
I know that a report from one of the big labs is best, but:

Can a reputable accredited appraiser pretty accurately determine if a ruby/sapphire has undergone heat treatment?....

Thanks!
widget

Yes, a reputable independent appraiser/lab can do this. Or at least I know a few that can

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I have mentioned this before - but the terms appraiser, lab are sometimes used independently and sometimes together in the decription of a place. When is an independent appraiser also a independent lab ? What are the characteristics and requirments for each service?

 

[widget]

I guess I was wondering if "labs" use equipment/methods for testing stones that plain, garden variety g.g. appraisers don''t usually have access to.

Years ago I bought a ruby that came with an appraisal (from a GIA accredited appraiser) that stated that the stone was unheated.

Later, that stone was sent to the GIA for a report, and it came back heat treated....

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[riogems]

I think this will depend on the lab and on the appraiser. I''m sure there is a mix of all out there -- many appraisers without any lab equipment, and some with the latest and greatest equipment.

 

[Richard Sherwood]

Determination of heat treatment is derived mainly from examination of the inclusions, so a gemologist with specialized training and a microscope capable of 100 plus magnification should be able to do it. It''s definitely "postgraduate" gemological work though, so only a minority of gemologists are really competent in this area.

The only problem is the credibility or "clout" of their opinion. Most people in the trade would tend to take GIA''s opinion over that of an independent gemologist, because of the GIA''s name recognition.

It''s not often the GIA is incorrect in treatment determination, by the way. They''re usually dead on the money.

The AGTA is an excellent lab with name recognition for this kind of work. They''re quick and reasonably priced (relatively speaking).