Geology and Development of the Lomonosov Deposit, North-Western Russia
Reviews diamond discoveries at the Lomonosov deposit, as well as the geology of the Arkhangelsk kimberlite province.
Dyed Purple Hydrophane Opal
Opals with an unusual purple bodycolour and strong play-of-colour have recently appeared in the market.
Play-of-colour opal from Wegel Tena, Wollo Province, Ethiopia
A new opal deposit was discovered in 2008 near the village of Wegel Tena, in the volcanic rocks of Ethiopia’s Wollo Province.
Beryllium Diffusion of Ruby and Sapphire
The heat treatment of corundum involving lattice diffusion of beryllium (Be) at temperatures over 1800°C has become a major issue in the gem trade.
Demantoid and topazolite from Antetezambato, Northern Madagascar: review and new data
An important deposit of andradite, containing demantoid and topazolite varieties, has been mined near the village of Antetezambato in northern Madagascar since early 2009.
Characterisation of Peridot from Sardinia, Italy
Gem-quality peridot is occasionally found as mantle xenoliths within basalts near Pozzomaggiore.
G. Robert Crowningshield: A Legendary Gemmologist
G. Robert (Bob) Crowningshield has made many significant contributions to the study of gems and the science of gemmology.
Yellow Mn-rich Tourmaline from the Canary Mining Area, Zambia
The most important source of yellow gem elbaite is the Canary mining area in the Lundazi District of eastern Zambia.
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.
A Gemological Pioneer: Dr. Edward J. Gübelin
During a career that spanned more than 65 years, the eminent Swiss gemmologist Dr. Edward J. Gübelin (1913–2005) built a monumental legacy.