Testing Yellow Sapphire — Passport to Obscurity
The examination of a yellow sapphire provides a lesson in the power of gemological microscopy.
Articles
Identifying Yellow Sapphire Using the Blue Filter
Introducing the blue filter as a gemological tool to separate natural and Verneuil synthetic yellow sapphires.
Verneuil Synthetic Corundum ID — Dangerous Curves
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.
Crystal Optics with the Refractometer
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.
Gem Testing with the Spectroscope
Many gemologists have difficulty mastering the direct-vision spectroscope. This article eases the pain.
Heat Seeker — UV Fluorescence as a Gemological Tool
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.
Fiber-Optic Light in Gemology — Living in the Dark Ages
The role of fiber-optic lighting in gemological microscopy.
Inside Out — Gem Inclusions & the Symmetry of Crystals
A discussion of how inclusion patterns mimic crystallographic symmetry in ruby and sapphire.
Padparadscha Sapphire & the Ownership of Words
A discussion of the definition of padparadscha sapphire, from early to modern times, along with the difficulty in standardizing such definitions.
Rutile in Corundum — Following the Silk Road
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.