Figure 1. The sparsely populated high desert of eastern Oregon is home to three localities producing natural copper-bearing labradorite feldspar. In this view of Lake County’s Dust Devil mine, the ...

The discovery of significant quantities of gem-quality sapphire in Minas Gerais could add corundum to the formidable list of gem species already commercially produced in Brazil. The presence of ...

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

A new microlithography process developed to create high-resolution diffraction grating patterns on portions of certain facets can improve the dispersion of light and thus the amount of “fire” in a ...

The refractive indices of the synthetic overgrowth on the beryl seeds of Lechleitner synthetic emeralds show a linear correlation with the chromium content of the coating. In a sample with refractive ...

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 ...

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 ...

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 ...

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 ...