ACS (American Chemical Society) cover story (article by Amanda Yarnell) on how heat treatment and chemical additives can make mundane stones look they are exclusive fancy/colored/rare diamonds/gems. A MUST READ before purchasing diamonds or gemstones!
Extensive calculator for estimating weight of gems and diamonds which are already set in jewelry. You need to take pretty exact measurements and know the type of cut as well as the depth of the stone which can be difficult to measure if the stone is already set. Still quite an interesting tool.
The private website of Richard Hughes containing dozens of articles on rubies, sapphires, and the mining areas where they are found. Richard Hughes, a gemologist working at the AGTA-GTC gem lab, is considered one of the best experts in the world on rubies and sapphires.
Provider of Exclusive (naturally) colored diamonds (fancy diamonds) for collectors and jewelry. Creator of the famous diamond collection at the American Museum of Natural History (AMNH) in New York since 1989. The Aurora collection has been exhibited at the London Natural History Museum.