Crystal Optics with the Refractometer • Lotus Gemology

The optical properties of crystals are intimately related to their crystal structures. This article examines the precise relationship between optic character and sign and crystal structure.

At the Lotus Gemology laboratory in Bangkok, we often get parcels of relatively uniform stones. But sometimes it is in this routine testing that we uncover surprises.

A look into the world of spinel inclusions that goes beyond simple octahedral crystals.

Solid inclusions have been used by gemologists as a means of determining origin. While there is a great deal of overlap from one source to another, there are also important differences. For example, while apatite has been identified in sapphire from Madagascar, Myanmar and Sri Lanka, apatite has never been identified in sapphire from Kashmir. Thus the purpose of this article is to give a full listing of solid inclusions in gem corundums from around the world, with each occurrence fully referenced. This is provided with the goal of making origin determination of ruby and sapphire more accurate.

For those who wish to explore the literature of inclusions in gemstones further, we have selected the following articles and books that are of particular merit. Most of these are cited in the Lotus Gemology Hyperion Inclusion Database, but are listed below in a more convenient summary format. Many of the links will allow you to download a PDF copy of the original article.

The best way to check the authenticity of a Lotus report is with online report verification.

When it rains red, it doesn't simply pour. It bleeds. Following closely on the heels of the ruby strikes in Mozambique, a major new find of the crimson stone is made in Madagascar.

Gem dealer, world traveler, activist, Dana Schorr passed away on 5 August 2015 at age 63, following a heart attack.

Lotus Gemology warns that oiled rubies, sapphires and spinels are entering the Bangkok wholesale market in increasing numbers. Most, but not all, of these gems are originating from Burma.

In 1878, the noted Austrian mineralogist, Gustav Tschermak von Seysenegg [1836–1927], was the first to properly identify silk in corundum, finding it to be composed of the mineral rutile (TiO₂). An English translation of his landmark paper is included, along with the original German version.