Green fluorite crystal under normal light (left) and UV light (right). In fact, in 1852, the physicist Sir George Gabriel Stokes named this effect 'fluorescence' after his studies of the mineral fluorite. However, this property is strongly associated with this gem. Thus, confirming the presence of this property isn't diagnostic for identifying fluorite. Some (but not all) fluorites display fluorescence under ultraviolet light (UV).

A craftsman at the Treak Cliff Cavern workshop in Derbyshire, England placed slices of Blue John, too thin for jewelry, on his window. However, a similar type of fluorite has been discovered in China. The Derbyshire deposits are nearly exhausted. This fluorite variety has bands of white, blue, violet, and reddish brown. What is 'Blue John' Fluorite?įor over 1,500 years, English artisans used Blue John or Derbyshire Spar as decorative material in vases, carvings, bowls, and so forth. (Materials from England and Cherbadung, Switzerland have demonstrated this). Licensed under CC By-SA 2.0.Ĭhemical impurities and natural irradiation contribute to fluorite's colorful varieties. Very rarely, some fluorites display a color change effect, from blue in daylight to purple or lavender in incandescent light. Atomic-age inspired sterling silver pendant with a rainbow fluorite stone. Lapidaries can cut multi-colored gems (sometimes called 'rainbow fluorites') from color zoned crystals, too. Chrome green material from Colombia and pink gems are rare. Most available stones occur in shades of purple, blue, or green. Many fluorite crystals are also transparent.įluorites come in many colors, including colorless. This means faceted fluorites can show exceptional brilliance. Do Fluorites Make Good Jewelry Stones?ĭespite its low refractive index (RI), fluorite can take a high polish.

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