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Jewelry, Gem & Gemology Acronyms

Our industry is full of acronyms referring to organizations, synthetic gem materials, and characteristics of stones. Below is a list of common acronyms and their definitions. We are hoping this will help sort out the mystery and shed some light on the secret language used within the esoteric cult of jewelers and gemologists.

AA-CJI - Accredited Appraiser of the Canadian Jewellers Institute
Anamolous Double Refraction
Accredited Gemmologist from the Canadian Institute of Gemmology
AGG = Aggregate
The American Gem Society
AGSL: The AGS Laboratory for Gem Testing

AGTA = American Gem Trade Association
AIGS = Asian Institute of Gemological Sciences
AM - Accredited Member of the American Society of Appraisers
ASA - Accredited Senior Appraiser of the American Society of Appraisers
B-/+ = Biaxial negative/positive
Be-heated, Be-treated = Beryllium treated sapphire
BR: Birefringence
ca: Critical angle
Cab: en-cabochon cut stone
CAPP - Certified Appraiser of Personal Property
CGA - Certified Gemologist Appraiser
CIBJO - Confédération International de la Bijouterie, Joaillerie, Orfèvrerie des Diamantes, Perles et Pierres
CMA - Certified Master Appraiser
CRI = Color Rendering Index
Certified Senior Member of the National Association of Jewelry Appraisers

ct - carat (gemstone weight)
CZ - Cubic Zirconia
DGemG: Graduate of the Deutsche Gemmologische Gesselshaft
DR: Double Refraction
EGL: European Gem Lab
FCC = Federal Communications Commission
FCGmA - Fellow of the Canadian Gemmological Association
FGA: Fellows of the Gemmological Association of Great Britain
FGAA - Fellow of the Gemmological Association of Australia
FGG:Fellows of the Deutsche Gemmologische Gesselschaft
= Federal Trade Commission
GG -
Graduate Gemologist. Awarded by the Gemological Institute of America
G&G - Gems & Gemology (GIA's trade journal)
G & J: Gems & jewellery (Gem-A periodical)
GGG: Gadolinium Gallium Garnet
GIA: The Gemological Institute of America
GTL - GIA's Gem Trade Laboratory
HPHT:High Pressure High Temperature treatment for diamonds
HSN = Home Shopping Network
ISA - International Society of Appraisers Accredited Member
J of G: The Journal of Gemmology (Gem -A periodical)
JA: Jewelers of America
JTV = JewelryTelevision
JVC: The Jewelers Vigilance Committee
kt - karat (metal purity)
MGA - Master Gemologist Appraiser
NAJA: National Association of Jewelry Appraisers
nD = refractive index with sodium light (589.3nm - Fraunhofer D-line)
RB: Round brilliant
RI: Refractive Index
SG: Specific Gravity
SRB - standard round brilliant (variant of RB)
TIR - Total Internal Reflection
U-/+ = Uniaxial negative/positive
YAG - Yttrium Aluminium Garnet

The following books are my recommendations for further study.
They are some of the best available.
If you would like a larger selection, please visit the Book Shop.

Gemstones: Symbols of Beauty and Power
by Eduard J. Gubelin, Franz-Zaver Erni

The Curious Lore of Precious Stones:

by George Frederick Kunz

Gemstone Buying Guide: A Guide to Buying

by Renee Newman

Gems: Their Sources, Descriptions and Identification...
by Robert Webster, Peter G. Read (Editor)