Identification of “Pistachio” Coloured Pearls Treated by Ballerina Pearl Co.
A report on the colour treatment process for these intensely greenish yellow to yellowish-green cultured pearls and the techniques for identifying them.
Reversible Colour Modification of Blue Zircon by Long-Wave Ultraviolet Radiation
Determines whether blue zircon, inadvertently altered to brown by exposure to long-wave UV radiation, can be restored to its original colour through the use of incandescent light.
Jaipur, India: The Global Gem and Jewellery Power of the Pink City
Examines Jaipur’s role as a coloured stone cutting and jewellery manufacturing centre, with profiles of 17 companies and their factory, trading and retail operations.
Inclusions in Natural, Synthetic and Treated Ruby
Provides a visual guide to the internal features of natural, synthetic and treated rubies.
Beryllium Diffusion of Ruby and Sapphire
The heat treatment of corundum involving lattice diffusion of beryllium (Be) at temperatures over 1800°C has become a major issue in the gem trade.
Characterisation of “Green Amber” With Infrared and Nuclear Magnetic Resonance Spectroscopy
A peridot-like bright greenish yellow to green gem material called “green amber” has recently appeared in the gem market.
Gem-Quality Andalusite from Brazil
Widely known as a rock-forming mineral, andalusite is not frequently encountered as a gem material.
Spectral Differentiation Between Copper and Iron Colourants in Gem Tourmalines
The authors used Vis-NIR spectral measurements combined with LA-ICP-MS data to investigate the usefulness of absorption spectra.
The Chinese red feldspar controversy: chronology of research up until July 2009
Red copper-containing plagioclase feldspar from Oregon has been available for over a century. In the early 2000s, new localities for copper-bearing feldspar were reported from the Democratic Republic of the Congo and from Tibet or an unspecified locality in China.
The Radioactive Decay Pattern of Blue Topaz Treated by Neutron Irradiation
A systematic study of 15 neutron-irradiated blue topaz samples was conducted using high-purity germanium (HPGe) digital gamma-ray spectroscopy.