Certifies the quality of diamonds according to cut, clarity, color and carat, and works to maintain consistency and accuracy in gemstone grading.

Offers services for the gemstone trade including a marketplace for buyers and sellers, and directories of cutters, grading labs and dealers.

Supplies an introduction to gemology through such categories as classifications, tools, and prices. Offers advice on collecting and cutting, too.

Scottish Gemological Association relays exhibit locations and suggests resources for gemology education. Includes a few related articles.

Swiss facility performs grading of diamonds, as well as tests to identify and classify cases of thermal enhancement in rubies and sapphires.

Organization represents the gemstone industry. Search the gem database by variety and color, find industry news, and read tips on gem shopping.

Learn gemology terms, explore lapidary work, and read tips on jewelry buying and making. Includes a directory of recommended suppliers.

Independent gem-certification and appraisal institute offers gemological training. Locations are in New York, Antwerp, Mubai and Bangkok.

Describes and discusses birthstones for each month from the modern era and according to such traditions as Arabic, Roman, Hebrew, and Hindu.

Conducts tests to certify the quality and authenticity of diamonds according to the 4C standard, and prepares reports on other natural gemstones.