Winter 2021 G&G Available Now
January 28, 2022
The Winter issue presents two characterization studies on gems from Mogok. These feature articles use Burmese blue sapphire and peridot of known provenance to enhance the current gemological knowledge base for origin separation. The third article combs through the early mining history of the Habachtal emerald deposit in Austria up to the beginning of World War I.
Blue Sapphires from Mogok, Myanmar: A Gemological Review
The lead article by Wasura Soonthorntantikul and co-authors investigates 248 blue sapphires collected from different areas in the Mogok Stone Tract by GIA field gemologists over five years. The gemological and chemical characterization indicates a wide range of blue color intensities, very consistent inclusion scenes, and no significant trace element differences between various sapphire-producing zones in Mogok. Such studies on reliable samples support the increasing demand for origin determination services by gemological laboratories.
Gemological Characterization of Peridot from Pyaung-Gaung in Mogok, Myanmar
Myanmar produces high-quality peridot of considerable size that possesses an attractive deep olive green color. A research team led by Montira Seneewong-Na-Ayutthaya examines peridot from the Pyaung-Gaung area and provides diagnostic inclusions and trace element chemistry that can separate this material from deposits in China and Pakistan.
History of Emerald Mining in the Habachtal Deposit of Austria, Part I
Karl Schmetzer details the mining history of Austria’s Habachtal region in part one of this two-part series. This article presents research using largely unpublished materials from Austrian and German archives to trace the various ownership transitions of this early emerald deposit.
GIA laboratory staff members present their latest findings in the Lab Notes section, including a diamond faceted as the iconic Apple logo, two pairs of antique Mughal spectacles with diamond and emerald lenses, and tourmaline featuring a unique surface pattern resembling a circuit board.
The Micro-World section, dedicated to the inner world of gemstones, features a chondrodite crystal in Burmese red spinel, an excellent example of a polyp structure in natural black coral, spectacular wispy “horsetail” inclusions in demantoid, and a tourmaline with abundant colorless zoning with windmill structures.
Colored Stones Unearthed
Colored gemstone deposits are geologically diverse and provide important information on the composition and evolution of the earth. The debut of this new G&G column explores geological concepts related to the formation of colored stones from the crust-mantle transition and below. Future installments will appear on a periodic basis.
Gem News International
Finally, GNI correspondents from around the world report on renewed interest in mining activity at the Yogo sapphire deposit in Montana, the identification of blue zircon supposedly from a new deposit in Malawi, Rio Tinto’s final sale of pink and blue diamonds from Argyle, and “floating flower” inclusions in a bangle fashioned from aventurine quartz.
Brooke Goedert is associate editor of Gems & Gemology at GIA in Carlsbad, California.