An Update on Color in Gems. Part 1: 

Introsuction and Colors Caused by Dispersed Metal Ions

Emmanuel Fristch
Gemological Institute of America
Santa Monica, California, USA

George R. Rossman
 California Institute of Technolgy, Pasadena, CA, USA


This is the first part in a three-part series on the origin of color in gem materials. This article discusses colors produced by individual metal ions in crystals

Gems and Gemology 23, 126-139