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.
Pleochroism in Faceted Gems: An Introduction
Describes the phenomenon of pleochroism and its complex effect on the appearance of coloured stones.
Colour Phenomena of Blue Amber
Investigates the presence of fluorescence, rather than iridescence, as the cause of colour in blue amber from the Dominican Republic and Indonesia.
Optimising Face-Up Appearance in Coloured Gemstone Faceting
How contrast patterns can increase perceived brightness and optimise a gemstone's appearance.
A History of Diamond Treatments
Modern gemmologists and diamantaires are faced with a broad spectrum of colour and clarity treatments ranging from the simple to the highly sophisticated.
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.
Modelling the Appearance of the Round Brilliant Cut Diamond: An Analysis of Fire, and More about Brilliance
This second major article in a three-dimensional modelling study analyses fire – the visible extent of light dispersed into spectral colours.
Classifying Emerald Clarity Enhancement at the GIA Gem Trade Laboratory
One of the greatest concerns with emerald filling is the degree of clarity enhancement such treatment represents
The Identification of Zachery-Treated Turquoise | Gems & Gemmology
Millions of carats of turquoise have been enhanced by a proprietary process called the Zachery treatment.