Summer 2022 G&G Available Now

Brooke Goedert

August 23, 2022

The Summer issue of G&G is bursting with new content! Three feature articles characterize gemstones—diamonds, amber, and nephrite, respectively—from known sources and offer the means to distinguish their geographic origin. Two additional full-length articles analyze gems from the coronation crown of Napoleon III and the unusual surface features of ekanite from Sri Lanka. Meanwhile, the journal’s regular sections continue to delight with interesting finds from around the world.

A LOOK AT DIAMONDS AND DIAMOND MINING IN GUYANA

The lead article by Roy Bassoo and Kenneth Befus combines direct observations, government reports, and historical accounts to provide a detailed gemological description of diamonds from Guyana. Their overview of diamond production describes the morphology, chemical content, and luminescence features of these alluvial diamonds prized for their clarity and color.

THE SHAPE OF EKANITE

Lutz Nasdala and coauthors characterize the physical properties, chemical composition, and general appearance of ekanite found in Ampegama, Sri Lanka, comparing them against samples from other deposits in the country. The remarkably uneven shapes and bumpy surface features of these ekanite fragments lead them to identify the processes responsible for the distinctive appearance.

A GEMOLOGICAL AND SPECTROSCOPIC STUDY WITH MOBILE INSTRUMENTS OF “EMERALDS” FROM THE CORONATION CROWN OF NAPOLEON III

In an effort to examine gemstones of historical significance, Stefanos Karampelas and fellow researchers use nondestructive mobile gemological and spectroscopic instruments to analyze 45 “emeralds” formerly set in the coronation crown of Napoleon III. Their efforts uncover the true identity of these gems, verifying that 41 are indeed natural emerald, probably of Colombian origin, while the remaining four are artificial glass.

CHARACTERISTICS OF NEWLY DISCOVERED AMBER FROM PHU QUOC, VIETNAM

A team led by Le Ngoc Nang discovers an amber deposit amid sandstone boulders on the island of Phu Quoc, Vietnam’s only known amber locality to date. Their article presents the gemological properties of this newly sourced amber and shows that FTIR spectroscopy can differentiate Phu Quoc from other global sources.

NATURAL RADIOACTIVITY IN SELECT SERPENTINITE-RELATED NEPHRITE SAMPLES: A COMPARISON WITH DOLOMITE-RELATED NEPHRITE

Dariusz Malzcewski and coauthors use low-background gamma-ray spectrometry to measure potassium, thorium, and uranium activity concentrations in nephrite from Poland, Russia, Canada, and New Zealand. Their studies prove that Th/U ratios appear unique according to geographic region. In addition, they conclude that nephrite does not pose a radiological risk to artisans or collectors who handle this ornamental material.

LAB NOTES

GIA’s global laboratory staff present their latest findings in the Lab Notes section, including an exceptionally rare 2.29 ct bright orange benitoite, the internally flawless 15.10 ct De Beers Cullinan Blue diamond, and a color-change sapphire exhibiting both asterism and chatoyancy.

MICRO-WORLD

The Micro-World section, dedicated to the inner world of gemstones, features a blue apatite crystal beautifully framed by rutile needles in garnet, an extensive network of eye-visible etch channels in diamond, and a labyrinth pattern in the fracture filling of an emerald.

COLORED STONES UNEARTHED

Colored Stones Unearthed returns to explore the fascinating realm of inclusions in gemstones. The microscopic inclusions within a gemstone can reveal a great deal about the host material. In this installment, learn how inclusions form, how they are studied, and what information gemologists and geoscientists can uncover.

GEM NEWS INTERNATIONAL

Finally, GNI contributors report on various topics ranging from gem identification to responsible practices to auction and museum highlights. Two entries feature gems that can change color—a photochromic zircon that reacted after exposure to long-wave UV and two sapphires that shifted between orange and yellow hues, providing an interesting case study on color stability. Gain insight on creating a sustainable and responsible emerald industry with Myne London, an ethical emerald supplier with a goal of supporting women’s economic empowerment in the gem trade. Finally, the spring 2022 auction season was buzzing with plenty of top-notch gems on the block, including two diamonds weighing more than 200 ct each and several gems fetching record prices.