Detecting Corundum Fillers with the Long-Wave UV Torch
There are many benefits to using a long-wave UV torch when testing ruby and sapphire. Here are a few examples.
Articles
Gem Treatment Disclosure — Notes from the Eastern Front
Discussion of gem treatment disclosure and its somewhat difficult history.
The Hardness of Fei Cui Jade — A Gemological Perspective
Jade has a long and varied nomenclatural history, with its definition altered in the current age for practical and cultural reasons. This paper examines the hardness of "fei cui" (pyroxene jade) and presents the findings in a simplified format based on empirical evidence and theoretical principles, while also considering the jade hardness data available in literature.
From Fei Cui to Jadeite and Back — Questions and Answers
Recent studies show that the gem known throughout the non-Chinese world as "jadeite" jade is actually a rock composed of three major mineral components – jadeite, omphacite and kosmochlor. These components grow in a submicroscopic aggregate with grains so small that normal lab instruments cannot easily determine the true composition. As a result, China's gem trade has adopted the traditional term "fei cui" (pronounced 'fay cho-y') to cover all the pyroxene jades. Lotus Gemology has done the same starting on 1 July 2023, dropping the names jadeite/omphacite/kosmochlor in favor of the scientifically more correct "fei cui."
Describing Color in Gems — A Fool's Guide
Color types such as "pigeon's blood," "Paraíba" and "cobalt blue" have become wildly popular in the gem trade. But there is a vast difference between coining such terms and applying them in a way that is both consistent and logical. Richard Hughes casts a critical eye on the subject.
Canary in the Ruby Mine — Low-Temperature Heating of Burmese Ruby
Detection of heat treatment below 1200°C in ruby and sapphire can present challenges to gemologists. In this study, the authors heated Burmese ruby samples and detailed the features that help in the detection of heat treatment.
Yellow Sapphires with Unstable Color
Some yellow sapphires contain unstable color centers. The following discussion outlines case studies of stones that faded after testing in the lab, and how color may be restored.
Apatite Oiling — Before and After
Oil treatment has a significant impact on the appearance of an apatite.
Vietnamese Skyline
Hogbomite-filled dislocations in a Vietnamese spinel.
An A-maze-ing Fingerprint in Spinel
A web-like fingerprint creates a maze-like pattern in spinel.