Blue Fluorite

Blue fluorite occurs at fluorite localities worldwide. Museum and collection gems cited by the International Gem Society include blue stones from Illinois (USA), pale blue from Korea and deep blue from Namibia; light-blue crystals from French mines and blue fluorite from Jinhua, Zhejiang, China have been studied for their color.

Blue fluorite has fluorite's very low refractive index (about 1.43), single refraction, hardness 4 and perfect cleavage, which separate it from harder blue gems. Very rarely, fluorite changes color from blue in daylight to purple or lavender in incandescent light. Irradiation can turn colorless or pale material darker blue. Fluorescence is common but not diagnostic, since not all fluorite fluoresces. Color can be lightened by heating or deepened by irradiation, and decorative pieces may be coated, dyed or plastic-impregnated.

Like all fluorite, it is soft (Mohs 4) and cleaves easily, so ring wear is not recommended; pendants, earrings and protective settings suit occasional wear. Store it apart from harder gems and out of strong light, since some fluorite fades with prolonged light exposure. Fluorite is slightly soluble in water: do not soak it, clean it only with a warm damp cloth, mild detergent and a soft brush, and avoid mechanical cleaning systems.

Pascle, a Japanese retailer, says fluorite is sometimes called the "stone of genius", and that blue fluorite is said to help one approach matters calmly and is recommended by the shop as a charm for study and work goals.