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Iridescence in iris quartz from Jalgaon, India

Causes of Iridescence in Natural Quartz

Xiayang Lin and Peter J. Heaney, May 8, 2017

Describes the occurrence of iridescence, and the role of differential etching, in quartz crystals from India’s Jalgaon District.

Figure 1. The Heart of Australia, a 3,510 ct double pseudomorph ikaite-calcite-opal gem specimen, is considered one of the finest ever unearthed. Courtesy of Graeme Dowton.

Rare Double Pseudomorph Ikaite-Calcite-Opal

Si Athena Chen and Jennifer Stone-Sundberg, May 23, 2023

One of the finest specimens of double pseudomorph ikaite-calcite-opal ever unearthed was on display at the Pueblo Gem & Mineral Show.

Figure 1. This relatively new type of violet chalcedony from Ethiopia (here, 75–198 ct) displays a wonderful pattern of white orbs. Photo by Annie Haynes; courtesy of Orbit Ethiopia Plc.

New Violet Orbicular Chalcedony from Ethiopia

Nathan Renfro, May 23, 2023

Tumble-polished freeforms of violet chalcedony with orb-like structures from a new find in Ethiopia were on display at GJX.

Figure 1. Left: The mother shell (<em>Mercenaria mercenaria</em>) and an 18K gold ring featuring a 14.43 × 14.63 mm lilac quahog pearl. Right: A rare collection of round quahog pearls ranging from 5.65 to 12.33 mm in diameter and in colors from white and beige to deep purple and tan. Photos by Robert Weldon; courtesy of ECIJA.

Exceptionally Rare Pearls from ECIJA

Si Athena Chen and Chunhui Zhou, May 23, 2023

An impressive variety of natural, wild, nacreous, and non-nacreous pearls were on display at the GJX show.

404.2 ct type IIa rough diamond from the Lulo mine in Angola used to fashion a 163.4 ct emerald-cut diamond.

Methods and Challenges of Establishing the Geographic Origin of Diamonds

Evan M. Smith, Karen V. Smit, and Steven B. Shirey, November 11, 2022

Examines the current available means of determining the geographic origin of gem-quality diamond, which are based largely on trace element and isotopic characteristics. For now, no method exists for determining the provenance of a random individual diamond.

Muling sapphires showcasing the wide range of color and clarity from this deposit.

Sapphire Beneath the Rich Black Soil of Muling, Northeastern China

Yimiao Liu and Ren Lu, November 11, 2022

A comprehensive look at the gemological features and advanced analysis of blue and fancy-color sapphire from the agricultural area of Muling, China.

Spectral Differentiation Between Copper and Iron Colorants in Gem Tourmalines

Paul B. Merkel and Christopher M. Breeding, August 23, 2009

The authors used Vis-NIR spectral measurements combined with LA-ICP-MS data to investigate the usefulness of absorption spectra.

Ekanite rough and cut stones appear yellowish green in transmitted light.

The Shape of Ekanite

Lutz Nasdala, K.A. Geeth Sameera, G.W.A. Rohan Fernando, Manfred Wildner, Chutimun Chanmuang N., Gerlinde Habler, Annalena Erlacher, and Radek Škoda, August 23, 2022

Discusses the unusual surface characteristics of ekanite from secondary deposits in Sri Lanka.

Ortho-nephrite samples analyzed are from Nasławice, Jordanów, Siberia, British Columbia, and New Zealand.

Natural Radioactivity in Select Serpentinite-Related Nephrite Samples: A Comparison with Dolomite-Related Nephrite

Dariusz Malczewski, Michał Sachanbiński, and Maria Dziurowicz, August 23, 2022

Uses gamma-ray spectrometry to directly measure internal radioactivity in green nephrite from deposits in Poland, Russia, Canada, and New Zealand.

Roraima Mountain (left) and outcrop of Roraima Supergroup rocks (right).

A Look at Diamonds and Diamond Mining in Guyana

Roy Bassoo and Kenneth Befus, August 23, 2022

Reports on diamonds from Guyana’s alluvial deposits, including mining history and practices.

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