Gemstones are often shrouded in mystery, waiting for the right team to tease out their origins and identifying characteristics. The Winter 2018 issue of Gems & Gemology reveals the color origins of breathtaking pink diamonds, the fascinating story behind Russia’s Amber Room, and insight into the rare natural “pipi” pearls from Pinctada maculata mollusks. Also included are the color origins of the color-change diaspore known as Zultanite; the unusual combination of corundum core and spinel rim that emerges from a deposit in northern Vietnam; and a new wall chart of internal features in natural, synthetic, and treated diamond.
Natural-Color Pink, Purple, Red, and Brown Diamonds: Band of Many Colors
Fancy-color diamonds in the pink to red range have been in the public eye thanks to the recent auction of the Winston Pink Legacy for $50 million. Gem-quality diamonds in this color range are exceedingly rare and highly valued. In this third article in& G&G’s series on colored diamonds, Sally Eaton-Magaña and her coauthors survey the characteristics of the more than 90,000 diamonds in the pink to red color range—which includes browns and purples—examined by GIA between 2008 and 2016.
The History and Reconstruction of the Amber Room
The original Amber Room, constructed for the king of Prussia, contained panels of magnificently carved and decorated Baltic amber. This sumptuous room was gifted to Russia in the early eighteenth century and eventually installed in the Catherine Palace near St. Petersburg. It remained in place until World War II, when German troops seized the panels and the palace was destroyed. The panels were last seen in 1945, and their disappearance remains a mystery. Russell Shor’s article recounts the history of the original Amber Room as well as the decades-long effort to faithfully restore it.
The Color Origin of Gem Diaspore: Correlation to Corundum
Color-change diaspore, also known as Zultanite, is an increasingly important material in the gem market. Che Shen and Ren Lu examine the material’s color origin using spectroscopy and laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS). Because gem diaspore and corundum are structurally similar and share the same chromophores, the study also compares the effectiveness of chromophores between the two.
Corundum with Spinel Corona from the Tan Huong–Truc Lau Area in Northern Vietnam
In primary and secondary placer deposits of Vietnam’s Tan Huong–Truc Lau area, it is not unusual to find rubies and sapphire with a spinel “rim” or corona. A team of researchers led by Nguyen Ngoc Khoi studied dozens of these specimens in an effort to explain the genesis of the corona. They theorize that during a certain stage of high-grade metamorphism, corundum reacts with biotite, garnet, or dolomite to form the spinel corona.
The Gemological Characteristics of Pipi Pearls Reportedly from Pinctada Maculata
Nanthaporn Nilpetploy and her coauthors review the rare natural pearls from the Pinctada maculata mollusk known as “pipi” pearls. Spectroscopic results showed some characteristic patterns in these small pearls, such as a distinct absorption feature around 495 nm in the UV-Vis spectra and peaks at 1380 and 1540 cm–1 in the Raman spectra. Findings from the study may aid in the separation of pipi pearls from material produced by other related mollusk species.
Inclusions in Natural, Synthetic, and Treated Diamond
Our chart series on the internal world of gemstones continues with diamond, displaying the most common inclusions in 30 stunning photomicrographs captured by Nathan Renfro, John Koivula, Jonathan Muyal, and Shane McClure. The foldout wall chart is accompanied by a short article about diamond inclusions and a suggested reading list.
Lab Notes
GIA’s labs around the world receive specimens that are striking or noteworthy. The Winter issue includes entries on a rare ruby from the state of Montana; a cat’s-eye Paraíba tourmaline from Brazil; and analysis of De Beers’ Lightbox CVD-grown diamonds.
Diamonds from the Deep
Our newest column focuses on the geology of natural diamonds. In this installment, Karen Smit and Steven Shirey explore the formation and importance of so-called “superdeep” diamonds, those that form outside of the conventional depths (150–200 km) within the mantle at depths of at least 410 to 660 km.
Micro-World
G&G’s quarterly gallery of gemstone inclusions offers a rose-shaped inclusion in a demantoid host, a zircon and monazite cluster in an Ethiopian sapphire, and a large, well-formed rutile inclusion in a rock crystal quartz.
Gem News International
Our correspondents from around the world contribute their most recent news and findings to the Gem News International section. This edition features preliminary observations of sapphires treated with heat and pressure, a coated pink synthetic moissanite, and a synthetic moissanite imitating a rough diamond.
2018 Dr. Edward J. Gübelin Most Valuable Article Award
Gems & Gemology once again invites our readers to vote on the three most important articles from the past year. Each completed ballot is entered into a drawing for a one-year subscription to G&G. Ballots for the 2018 Most Valuable Article Award must be submitted by March 11, 2019.
Jennifer-Lynn Archuleta is the editor of Gems & Gemology.
Gemstones are often shrouded in mystery, waiting for the right team to tease out their origins and identifying characteristics. The Winter 2018 issue of Gems & Gemology reveals the color origins of breathtaking pink diamonds, the fascinating story behind Russia’s Amber Room, and insight into the rare natural “pipi” pearls from Pinctada maculata mollusks. Also included are the color origins of the color-change diaspore known as Zultanite; the unusual combination of corundum core and spinel rim that emerges from a deposit in northern Vietnam; and a new wall chart of internal features in natural, synthetic, and treated diamond.
Natural-Color Pink, Purple, Red, and Brown Diamonds: Band of Many Colors
Fancy-color diamonds in the pink to red range have been in the public eye thanks to the recent auction of the Winston Pink Legacy for $50 million. Gem-quality diamonds in this color range are exceedingly rare and highly valued. In this third article in& G&G’s series on colored diamonds, Sally Eaton-Magaña and her coauthors survey the characteristics of the more than 90,000 diamonds in the pink to red color range—which includes browns and purples—examined by GIA between 2008 and 2016.
The History and Reconstruction of the Amber Room
The original Amber Room, constructed for the king of Prussia, contained panels of magnificently carved and decorated Baltic amber. This sumptuous room was gifted to Russia in the early eighteenth century and eventually installed in the Catherine Palace near St. Petersburg. It remained in place until World War II, when German troops seized the panels and the palace was destroyed. The panels were last seen in 1945, and their disappearance remains a mystery. Russell Shor’s article recounts the history of the original Amber Room as well as the decades-long effort to faithfully restore it.
The Color Origin of Gem Diaspore: Correlation to Corundum
Color-change diaspore, also known as Zultanite, is an increasingly important material in the gem market. Che Shen and Ren Lu examine the material’s color origin using spectroscopy and laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS). Because gem diaspore and corundum are structurally similar and share the same chromophores, the study also compares the effectiveness of chromophores between the two.
Corundum with Spinel Corona from the Tan Huong–Truc Lau Area in Northern Vietnam
In primary and secondary placer deposits of Vietnam’s Tan Huong–Truc Lau area, it is not unusual to find rubies and sapphire with a spinel “rim” or corona. A team of researchers led by Nguyen Ngoc Khoi studied dozens of these specimens in an effort to explain the genesis of the corona. They theorize that during a certain stage of high-grade metamorphism, corundum reacts with biotite, garnet, or dolomite to form the spinel corona.
The Gemological Characteristics of Pipi Pearls Reportedly from Pinctada Maculata
Nanthaporn Nilpetploy and her coauthors review the rare natural pearls from the Pinctada maculata mollusk known as “pipi” pearls. Spectroscopic results showed some characteristic patterns in these small pearls, such as a distinct absorption feature around 495 nm in the UV-Vis spectra and peaks at 1380 and 1540 cm–1 in the Raman spectra. Findings from the study may aid in the separation of pipi pearls from material produced by other related mollusk species.
Inclusions in Natural, Synthetic, and Treated Diamond
Our chart series on the internal world of gemstones continues with diamond, displaying the most common inclusions in 30 stunning photomicrographs captured by Nathan Renfro, John Koivula, Jonathan Muyal, and Shane McClure. The foldout wall chart is accompanied by a short article about diamond inclusions and a suggested reading list.
Lab Notes
GIA’s labs around the world receive specimens that are striking or noteworthy. The Winter issue includes entries on a rare ruby from the state of Montana; a cat’s-eye Paraíba tourmaline from Brazil; and analysis of De Beers’ Lightbox CVD-grown diamonds.
Diamonds from the Deep
Our newest column focuses on the geology of natural diamonds. In this installment, Karen Smit and Steven Shirey explore the formation and importance of so-called “superdeep” diamonds, those that form outside of the conventional depths (150–200 km) within the mantle at depths of at least 410 to 660 km.
Micro-World
G&G’s quarterly gallery of gemstone inclusions offers a rose-shaped inclusion in a demantoid host, a zircon and monazite cluster in an Ethiopian sapphire, and a large, well-formed rutile inclusion in a rock crystal quartz.
Gem News International
Our correspondents from around the world contribute their most recent news and findings to the Gem News International section. This edition features preliminary observations of sapphires treated with heat and pressure, a coated pink synthetic moissanite, and a synthetic moissanite imitating a rough diamond.
2018 Dr. Edward J. Gübelin Most Valuable Article Award
Gems & Gemology once again invites our readers to vote on the three most important articles from the past year. Each completed ballot is entered into a drawing for a one-year subscription to G&G. Ballots for the 2018 Most Valuable Article Award must be submitted by March 11, 2019.
Jennifer-Lynn Archuleta is the editor of Gems & Gemology.
