Gemstone Enhancements
The term “enhancement” is defined as any treatment or process other than cutting and polishing that improves the appearance (color/clarity/phenomena), durability, value or availability of a gemstone. In today’s gem marketplace, many gemstones have been enhanced by a variety of methods. Such processes may range from simple heating (such as with tanzanite) to high-tech irradiation (such as blue topaz).
    The AGTA GTC takes enhancement disclosure seriously, which is why full enhancement disclosure is an important part of our gemological reports. Indeed, the AGTA member guidelines are the most stringent in the industry. To view the full AGTA enhancement manual, see the following link:

American Gem Trade Assocation Gemological Testing Center
18 East 48th St., Suite 502
New York, NY 10017, USA
Tel: 212-752-1717; Fax: 212-750-0930
E-Mail:; Web:
© 1999–2005 American Gem Trade Assocation Gemological Testing Center. All rights reserved. Users may download this information for their own private, non-commercial use. Any other reproduction of this document (text or graphics) without the express written consent of the AGTA GTC is strictly prohibited.
Problems? Praise? Contact the Webmaster.


The AGTA GTC publishes free bulletins with the latest gem news. Sign up here.


Site Search

search tips     sitemap