Past conferences
Abstracts Library
Purple to bluish grey chalcedony from Ethiopia
In the past 15 years, Ethiopia has repeatedly gained attention for a variety of new gem finds. In 2008, a large deposit of white play-of-colour opal was found (Rondeau et al., 2010
Additional Observations on Unstable Color in Padparadscha Sapphires
For the past few years laboratories have been testing the color stability of padparadscha sapphires. It became an issue because we realized that the orange color in some pads was u
Cobalt spinel from Bai Buoi mine, Yen Bai, Vietnam
The cobalt bearing spinel from Lukande, Tanzania, discovered in 2019, has attracted much attention and several papers were published recently (Stephan & Muller., 2022, Krzemnicki e
Violet Diamonds from Argyle: New Insights into the Cause of their Unique Color
Until its recent closure, the Argyle mine in Australia has been the only source of uniquely colored violet diamonds produced during the 35 years of its operation. These diamonds th
Snapshot of rubies from 1915
In 2008 the Honourable Mary Montagu Scott oversaw the opening of a permanent exhibition at Buckler’s Hard Maritime Museum on the Beaulieu Estate about the steamship SS Persia (Fi
Influence of Irradiation on Colour Modification and Colour Stability of Rubies: A Preliminary Study
Ruby is the chromium-bearing red colour-variety of corundum Al2 O3 . Since historic times, ruby is highly popular in the gem and jewellery market because of its highly saturated re
Baltic amber and its inclusions: an insight into the origin and nature of the trapped material
Amber is a fossilised resin from ancient trees (coniferous and deciduous), which underwent the process of fossilisation in various epochs and depositional environments. Until the p
Opal stability: a step toward detection
Opal is a gem of captivating beauty that stems from its complex microscopic structure composed mainly of silica. In the most striking specimens, the light diffraction from a three-
Low Temperature Heat Treatment of Burmese Ruby
Detection of low-temperature heat treatment (below 1200°C) in ruby and sapphire can present challenges to gemologists, as alterations to the material are often subtle. In this stu
Colour varieties of gems – where to set the boundary?
In theory it is simple: a gemstone is a mineral formed in nature by geological processes and, as such, it has a mineralogical name that is scientifically defined and accepted by th
Gemmological studies of “Hybrid Diamond” (Natural + CVD synthetics)
Size and quality of CVD synthetic diamonds for jewelry market have been improved over the years, and various fancy colour CVD diamonds have also been produced. In addition, overgro
Origin Identification Characteristics of High-quality Green Jadeite
Currently occurrences of jadeite mainly include Myanmar, Guatemala, Russia, Kazakhstan and Japan. Origin has a great impact on the price of high-quality green jadeite and at presen
Study of a historical Alexandrite from Paris school of mines collection
Rare are the scientific studies on exceptional gemstones belonging to museum collections. This investigation is part of an ongoing project, on the study of historic gems, of the Mi
Blue shortwave luminescence of gems: the role of titanate groups
The purpose of this study is to describe Blue Shortwave-UV excited Luminescence (BSL) in gems and related materials, and demonstrate the role of titanate groups in a number of gems
A study of nickel-bearing type Ia diamonds
We present a detailed FTIR and PL spectroscopic study (i.e. at 298 and 77°K) of a large number of colorless (i.e. color D to G) type Ia diamonds (i.e. >200), showing the presence
Causes of color in brown mammoth ivory
The mammoth species were once the largest terrestrial mammals in the world during the late Pleistocene (approximately 350,000 to 10,000 years ago), inhabiting the northern hemisphe
A nuummite occurrence from kangerluarsuk in the Maniitsoq Region, West Greenland
K. I. Giesecke was the first to recognize the beauty of the iridescent amphibolitic gemstone Nuummite in 1810 when he collected samples from the island Simiuttat in the Nuuk area,
Color enhancement in yellow sapphire
Natural yellow sapphire is colored by one or the combination of two different chromophores, Fe3+ and the trapped hole-Fe3+ (h• -Fe3+) colour center. Fe3+ chromophore is typically
A study of Chikayama’s gem and mineral collections and building a gem museum
Based on the belief that “a gemstone is art and science,” Mr. Akira Chikayama devoted his life to gemological research and study for the benefit of people involved in gemstones
Nacreous Blister Pearl Discovered in Edible Oyster (Crassostrea gigas)
A baroque pearl with a gray, nacreous appearance was discovered attached to the interior of an edible oyster while the author was enjoying a meal at home. The oyster had been purch
