Feature Gems & Gemology, Winter 1981, Vol. 17, No. 4

Gem Garnets in The Red-To-Violet Color Range

The gemological classification of garnets has been thrown into question with the appearance on the market of new types of garnets that do not fit into the traditional system of description. The question of what criteria should be used to classify both old and new types of garnets is approached in this article through the study of 96 red-to-violet gem garnets. While the color of gem garnets is of paramount importance, color being both their most obvious feature as well as their principal claim to beauty, this article shows that the characteristic of color appears to have little correlation with variations in bulk (not trace) composition or physical properties. Analysis of the gemological properties, chemical composition, and CIE color coordinates of the stones studied led to the more specific definition of the widely accepted terms pyrope, almandine, and rhodolite for meaningful gemological classification. This article represents the first in a series of studies aimed at developing an effective terminology for the characterization of gem garnets.