Gem Virtuosos: The Drehers and Their Extraordinary Carvings
A look at the artistic heritage of the Drehers, an influential family of gem carvers in Idar-Oberstein, Germany.
Amethyst from Boudi, Morocco
An introduction to Moroccan amethyst, which features distinctive color zoning and inclusions.
Amethyst from Four Peaks, Arizona
For more than a century, the Four Peaks mine in Maricopa County, Arizona, has produced gem-quality amethyst.
The 3543 CM-1 Infrared Absorption Band in Natural and Synthetic Amethyst and its Value in Identification
The proper use and limitations of IR spectroscopy for identifying natural versus synthetic amethyst of various types have been investigated, focusing on the region 3800–3000 cm-1.
Amethyst Mining in Brazil
Brazil is currently the leader in overall production of amethyst.
A Simple Procedure to Separate Natural from Synthetic Amethyst on the Basis of Twinning
Where there are no inclusions or colour zoning, the presence of Brazil twinning in the natural amethyst will usually make the distinction.
"Damsonite," the trade name for a new type of chalcedony, is analysed and described.
A Status Report on Gemstones from Afghanistan
An overview of the plentiful and various gem materials being discovered and produced in Afghanistan.
Artificially Induced Colour in Amethyst-Citrine Quartz
A new and rather unusual gem material and possible treatments are discussed.
Infrared Spectroscopy of Natural vs. Synthetic Amethyst: An Update
When microscopic identification is not feasible, FTIR spectra at high resolution (0.5 cm–1) can distinguish natural and synthetic amethyst.