Blue Sapphires from Mogok, Myanmar: A Gemological Review
A gemological analysis of blue Burmese sapphires from Mogok, based on a series of field expeditions over the last decade.
History of Emerald Mining in the Habachtal Deposit of Austria, Part I
Contributes to the mining history of Austria’s Habachtal region, which is believed to be one of the earliest emerald deposits.
Gemological Characterization of Peridot from Pyaung-Gaung in Mogok, Myanmar
Examines the mining and the internal, spectroscopic, and chemical features of peridot from this deposit, which possesses a rich olive green color and is available in large sizes.
Color-Zoned Cat’s-Eye Chrysoberyl
The Tokyo lab recently identified a unique localized distribution of cloud-like inclusions in a chrysoberyl.
Star Rhodochrosite
The Carlsbad lab received a rhodochrosite cabochon featuring rhomboid-shaped fluid inclusions, causing a four-rayed star.
Colored Stones from the Deep
The first installment of this column discusses the formation of colored stones from the crust-mantle transition and below.
Burmese Blue Sapphire and Peridot from Mogok and a History of Emerald Mining in Habachtal, Austria
An overview of the Winter 2021 Gems & Gemology content.
Banded Turquoise from Zhushan County, Hubei Province, China
Researchers examine six specimens of banded turquoise, obtained through long-term cooperation of local miners in Zhushan County.
Blue Zircon Reportedly from Malawi
A reported new source of blue zircon in Malawi yields rough material for beautiful finished stones in the gem trade.
Two Antique Mughal Spectacles with Gemstone Lenses
Unique diamond- and emerald-lensed spectacles from the Mughal Empire were tested in GIA’s New York laboratory.
Chondrodite in Red Spinel from Mogok, Myanmar
The Bangkok lab recently encountered a single round crystal of chondrodite in red spinel, a possible indicator of Burmese origin.
Faceted Demantoid Garnet with Spectacular “Horsetail” Inclusions
Remarkable “horsetail” inclusions discovered in a demantoid garnet, while their origin and composition remain under discussion.
Monazite (?) in Quartz
Analysis of a transparent yellow angular crystal inclusion in a Brazilian rock crystal quartz host suggests monazite.
Radioactive Green Diamond
The Carlsbad lab recently encountered a 2.42 ct green diamond showing signs of radiation treatment by the use of radioactive salts.
Rainbow Graining in Diamond
One of the more subtle inclusion scenes gemologists sometimes observe in natural diamonds is the presence of crystallographically oriented structural defects known as “internal graining.”
Spiral Nacre in Natural Pearl
Nacreous pearls are known to have platelet growth resembling fingerprints or topographic maps, but a less common appearance is nacre with a concentric spiral pattern.
Biogenic Carbon in Pink Corundum from Southern West Greenland
Recent studies of pink corundum in Greenland suggest that the presence of graphite created the conditions that facilitated corundum formation.
GSA Meeting – GIA Session
An overview of GIA’s presentations at the annual Geological Society of America (GSA) meeting held in Portland, Oregon.
Vaterite Found on a Strand of Freshwater Cultured Pearls
An unusual formation of vaterite was identified on the surface of numerous freshwater cultured pearls throughout a single strand.
Unique Circuit Board–Like Surface Pattern on Tourmaline
Microscopic observation by the Tokyo lab revealed a mysterious networked pattern, resembling that of a circuit board, covering the overall surface of a blue-green tourmaline.
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