Synthetic Star Sapphires and Rubies Produced by Wiede’s Carbidwerk, Freyung, Germany
Details the process used by Wiede’s Carbidwerk to produce star synthetic corundum from the mid-1950s until the 1970s.
Causes of Iridescence in Natural Quartz
Describes the occurrence of iridescence, and the role of differential etching, in quartz crystals from India’s Jalgaon District.
Cutting Diffraction Gratings to Improve Dispersion (“Fire”) in Diamonds
A new microlithography process developed to create high-resolution diffraction grating patterns on portions of certain facets can improve the dispersion of light and thus the amount of “fire” in a diamond.
Update on Ammolite Production from Southern Alberta, Canada
There have been a number of changes in Ammolite production from southern Alberta, Canada, since 2001.
The Hidden Beauty of Amber: New Light on an Old Subject
The surprising inner world of inorganic inclusions in amber is explored through the use of polarised light and microscopic techniques.
Abstracts; Summer 2009
This article, from the Summer 2009 issue of Gems & Gemmology, is a compilation of abstracts of important gemmology-related articles published outside of Gems & Gemmology.
Hackmanite/Sodalite from Myanmar and Afghanistan
Significant amounts of gem-quality sodalite/hackmanite—some unusually transparent—have been produced.
Treated-Colour Pink-To-Red Diamonds from Lucent Diamonds Inc.
Using a multi-step process, Lucent Diamonds has developed a new treatment process for certain natural diamonds that creates colours from pink-purple to red to orangey brown.
Reactor-Irradiated Green Topaz
Examination of samples of faceted "Ocean green" topaz reveals that this material has been irradiated in a nuclear reactor.
Pyrope-Spessartine Garnets with Unusual Colour Behaviour
Unusual colour-change garnets.