Books: Gemstones of the World
Review of Walter Schumann's Gemstones of the World.
Optical Effects of Phenomenal Cabochons
Learn how the structure, inclusions and properties of some gemstones interact with light to create unusual visual effects.
Reversible Color Modification of Blue Zircon by Long-Wave Ultraviolet Radiation
Determines whether blue zircon, inadvertently altered to brown by exposure to long-wave UV radiation, can be restored to its original color through the use of incandescent light.
Gray-To-Blue-To-Violet Hydrogen-Rich Diamonds from the Argyle Mine, Australia
The Argyle diamond mine is the only known source of type IaB hydrogen- and nitrogen-rich diamonds colored gray to blue to violet.
Gem-Quality Andalusite from Brazil
idely known as a rock-forming mineral, andalusite is not frequently encountered as a gem material.
A Foundation for Grading the Overall Cut Quality of Round Brilliant Cut Diamonds
The GIA diamond cut grading system described here includes the components of brightness, fire, scintillation, polish, and symmetry, as well as weight and durability concerns, into a single overall grade for cut quality for standard round brilliants.
Aquamarine from the Masino-Bregaglia Massif, Central Alps, Italy
Aquamarine from granitic pegmatites of the Masino-Bregaglia Massif, Central Alps, Italy.
Chrysoberyl from the New England Placer Deposits, New South Wales, Australia
Examines a collection of chrysoberyl samples from these sapphire placer deposits to determine their distinct mineralogical and chemical properties.
Mixed-Type Cape Diamond
A Fancy orangy yellow “cape” diamond featured an unexpected 480 nm band, a defect normally associated with orange color.
Dual-Color Double Stars in Ruby, Sapphire, and Quartz: Cause and Historical Account
Examines a form of asterism comprising two six-rayed stars, one white and one that exhibits the stone’s bodycolor. Firsthand accounts and a survey of patent documents reveal that diffusion has been used to create or enhance this optical phenomenon in synthetic and possibly natural corundum since the 1950s.