Gems & Gemology Vol. 56 Issue 3 (Fall 2020)
Author : Gemological Institute of America
This issue offers an exciting glimpse into the world of D-to-Z diamonds, characterizes the inclusion features and chemical composition of emeralds from Swat Valley, and details the acquisition and auction of crown jewels by European royalty. In the lead article, a GIA team led by Sally Eaton-Magaña and Christopher M. Breeding examines colorless to light yellow/brown diamonds with a “D-to-Z” color grade, which make up the vast majority of the world’s gem diamond trade. Because this group of mostly type Ia diamonds has not been subjected to HPHT decolorizing treatment or laboratory growth, researchers usually investigate their more rare diamond type counterparts. This study evaluates diamond type properties and grading quality factors of D-to-Z diamonds submitted to GIA in 2017 and sheds light on their unique geological formation story.
MARC INFORMATION