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Round Dumortierite Cabochon
ORTHORHOMBIC

Dumortierite

AlAl6O3BSi3O18

Hardness
7
Refractive Index
1.67–1.72
Spec. Gravity
3.3–3.4
System
Orthorhombic
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Dumortierite is a minor blue gemstone that usually forms as inclusions in Quartz. Its most common color is blue or grayish-blue, though pink and purple colors are also known. Dumortierite's durability, combined with a high hardness, would make this an ideal gemstone, but the lack of transparency and often dull luster limit its use. 

About

Pure Dumortierite gemstones are rarely encountered. Most lapidary-grade Dumortierite is dense blue inclusions of Dumortierite within Quartz. These gemstones are often called by the confusing term "Dumortierite Quartz", or may even be called "Blue Quartz". The inclusions can be present throughout the Quartz, or in splotches or zones, resulting in light and dark blue color zones.

The properties listed above are inherent to pure Dumortierite. However, since most Dumortierite gemstones are actually Quartz with Dumortierite inclusions, the properties listed under Quartz are the more accurate gemstone reference.

Uses

Dumortierite is a minor gemstone used mostly in cabochons and lapidary carvings.

Varieties

✓ common  · ✗ uncommon

Treatments & Enhancements

Dumortierite gemstones are natural and not treated or enhanced.

Sources

Dumortierite sources include Brazil, Peru, Madagascar, Namibia, Austria, and the U.S. (California).

Similar Gemstones

Further Reading

Faceted

In the Rough