Danburite is a silicate of calcium and boron, which is occasionally encountered as a faceted gemstone. The mineral is reasonably durable, due to its relatively high hardness (7.0-7.5) and lack of vulnerable directional cleavages. In addition, crystals can be found in sufficiently large sizes for faceting into stones of up to five carats. However, danburite’s popularity as a gemstone has been held back by its limited name recognition amongst the jewelry-buying public and the lack of a constant and reliable supply of facetable material.
Named in 1839 after its original source locality of Danbury, Connecticut, most danburite gemstones encountered within the marketplace have been faceted from colorless to pale pink Mexican crystals. However, Myanmar’s famous Mogok gemstone tract is an important source for the preferred yellowish and/or brownish material, with these stones becoming more rare and valuable as their hue saturation increases.