Canadian Gemmological Association

The Gemmological Association and Gem Testing Lab of Great Britain

Gemological Institute Of America

The German Gemmological Association

The Canadian Institute of Gemmology

International Gemmological Institute

American Gem Society

Harold Weinstein Ltd. Independent Gem Lab

GemScan International Inc.

Independent Gemmological Services

Canadian Jeweller Magazine

Polygon Net - Jewelry Industry

International Colored Gemstone Association