corundum

A discussion of the literature of ruby and sapphire (corundum), with particular emphasis on the most collectible books covering ruby and sapphire around the world.

A brief description of the color types for ruby and sapphire used at Lotus Gemology.

A loving look at ruby – the gem of passion – from the standpoint of the connoisseur.

A discussion of rutile silk in corundum and its use in detecting artificial heat treatment. Careful examination of these "silk" inclusions can provide vital clues to unmask heated gems.

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.

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 Burmese sapphire shows a celestial scene both externally and internally.

In search of ruby and sapphire on the lost Isle of Madagascar.

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

In search of Thailand's last ruby miner.

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.