In January 2012, aquamarine crystals containing interesting inclusions were extracted from the Ambatofotsikely area northwest of Antsirabe, Madagascar. These specimens displayed various types of ...

Over the past several years, diamond simulants have entered the market that consisted of colorless cubic zirconia reportedly coated with a thin layer (e.g., represented to be 30–50 nm) of ...

Figure 1. These 20 completely non-nacreous pen pearls, from the group of 22 samples in this study, are set against a pen shell displaying both nacreous (left) and non-nacreous areas (right). Photo by ...

During the last 20 years, Australia has assumed a major role in the production of blue sapphire. Most of the gem material comes from alluvial deposits in the Anakie (central Queensland) and New ...

This note deals with some gemological applications for a tool well known to microscopists: the first-order red compensator. In gemological microscopy, the compensator can be useful in locating ...

If you were born in the month of June, you are lucky enough to have three birthstones to call your own. June is one of only three months (the others are August and December) that has three birthstones ...

Large crystals of the rare-earth carbonates bastnäsite-(Ce) and parisite-(Ce) have been collected from alkaline pegmatites at Malawi’s Mt. Malosa, where they occur associated with aegirine, microcline ...

Renewed interest in large-scale commercial mining of Montana sapphires motivated a detailed study of the heat treatment of sapphire from the Rock Creek deposit. During the course of this systematic ...

Ruby and sapphire of natural or synthetic origin can be heat treated to improve asterism; to remove asterism or silk; to improve, add, or remove color; and even to alter imperfections. At least nine ...

During the past 25 years, the corundum market has been transformed from one of medium to high-priced gems to one that encompasses nearly all price ranges. This transformation was caused by the ...

For more than a century, the Four Peaks mine in Maricopa County, Arizona, has produced gem-quality amethyst from crystal-lined or crystal-filled cavities and fractures in a brecciated quartzite host ...

The various techniques in use today to alter colorless topaz to produce brown, pink, and most commonly, blue stones are discussed. Special attention is given to the three irradiation sources -gamma ...