Sapphire is one of the classic gems. In this article, Lotus Gemology's resident connoisseur casts a discerning eye at the factors that contribute to quality in this legendary precious stone.

A history of spinel, including balas ruby and lodestone.

Since the turn of the millennium, the price of fine spinel has risen at an incredible pace. No longer simply the poor man's ruby, spinel is finally getting the attention it deserves as one of the world's premier gems.

Digital Devil #10. It was Tucson. Show over. The last supper. One of those marvelous evenings which Tucson regularly delivers…

In 1991, titanium-diffused blue sapphires reappeared in the Bangkok market after an absence of many years. Touted as "deep diffusion," the stones proved to have no greater color penetration than the original Union Carbide product.

An introduction to the green grossular garnet known as tsavorite, it's history, occurrence in East Africa, and geology.

One of the greatest gemological challenges is determining if a ruby or sapphire has been heat treated. UV fluorescence can assist in that identification, as well as detecting fillers in emerald.

Virtually all gemologists are aware of the curved growth lines and gas bubbles in Verneuil (flame-fusion) synthetic corundum, but few understand exactly why they occur and how they are distributed in these stones. This article clarifies these important identifying features.

Digital Devil #5, where I transition from hard-nosed gemological gumshoe to lamenting the lack of romance and appreciation of beauty in gemology.

The examination of a yellow sapphire provides a lesson in the power of gemological microscopy.