DiamondonNet Dictionary
DiamondonNet dictionary of common loose diamonds and diamond jewelry terms in the industry and their meanings.
Click on the letters below and choose the word or phrases you'd like to learn.

Select a Letter: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | SHOW ALL

Independent Gemological Laboratories

A diamond grading certificate is a report given by an independent and professional gemological laboratory. The diamond is evaluated for its quality, not its value. Every diamond is unique. The certificate will map out all the diamond's recognizable and individual characteristics. Each certificate will include the diamond's color, clarity, carat weight and cut information (see the 4 C's). The grading report also includes a hand-drawn map of the diamond's inclusions. Since no two diamonds are exactly alike you can always check that the certificate matches the diamond.

When it comes to certification and appraisal, you need absolute accuracy, precision and reliability. That is why our stones are appraised by two of the most respected laboratories in the Trade.

GIA logo
An independent nonprofit organization, the Gemological Institute of America (GIA) is renowned for its impartial service as the world's foremost authority in gemology. The Institute's history of ground-breaking scientific research, education, and gemological laboratory services reads as a virtual chronicle of the industry's own growth and sophistication.

From 1953, when Richard T. Liddicoat created and introduced the International Diamond Grading System™ - to the position the Institute holds today as the most respected grading and identification authority in the world - GIA has combined the principles of research, education, and service to help gem and jewelry professionals around the globe use science and product knowledge to sustain the public's trust.

The GIA can be reached at:

Gemological Institute of America (GIA)
World Headquarters
The Robert Mouawad Campus
5345 Armada Drive
Carlsbad, California 92008
Telephone: (800) 421-7250 or (760) 603-4000
E-mail: ghill@gia.edu
EGL USA logo
EGL USA is one of the largest and oldest independent gemological institutions focusing on gemstone certification and research. Originally part of an international network founded in Europe in 1974, EGL USA opened its first U.S. lab in the heart of New York's international diamond and jewelry district in 1977. In 1986 EGL USA became independently owned. Today the EGL USA Group has laboratories in New York City, Los Angeles, Vancouver, and Toronto.

EGL USA is not affiliated with any other EGL labs outside North America.

Every certificate issued by our lab states "A member of the EGL USA Group." Certificate numbers are preceded by either "US" or "CA," to indicate country of origin and to provide consumers the assurance that their certificate has been issued by a member of the EGL USA Group.

In 1999 EGL USA initiated a Research Department to respond to the changing needs of the jewelry industry. It is one of only a few labs worldwide doing advanced research in gemology.

The EGL can be reached at:

6 West 48th Street
New York, NY 10036
Telephone: 212-730-7380
Fax: 212-842-5180
E-mail: egl@eglusa.com

And @

EGL USA/Los Angeles
550 South Hill
Suite 840
Los Angeles, CA 90013
Telephone: 877-893-8593
Fax: 213-534-2224