However, the English naturalist Philip Skippon (1641–1691) stated that one Monsieur Lort, of Montpellier, France, a "counterfeiter" of "amethysts, topazes, emeralds, and sapphires" found that on heating " fluor smaragdi" (Latin for "flowing emerald/beryl/jasper") in a pan of coals and afterwards "putting it in a dark place (it) shines very much: At the same time several other stones were tried but did not shine." (1732 6: 718). In 1833, David Brewster discovered the fluorescence of the mineral fluorite or fluorspar. Josiah Wedgwood, in 1792, found phosphoresce from rubbing together two pieces of quartz or of agate, and wrote that the ruby gives "a beautiful red light of short continuance." Edmond Becquerel reported in 1861 that ruby fluoresces better than sapphire, red feldspar fluoresces, and crushed orthoclase will flame. In 1735, the French chemist Charles François de Cisternay du Fay determined that lapis lazuli, emerald, and aquamarine were luminescent. The luminescent Bologna Stone (impure barite), which was discovered by Vincenzo Cascariolo in 1602, was sometimes called " lapis lunaris" ("lunar stone"), because, like the moon, it gave out in the darkness the light it received from the sun (Kunz 1913: 168).
According to Prafulla Chandra Ray, the Indian king Bhoja (r. 1193–1280) and it was apparently rediscovered by Robert Boyle in 1663, who also found that some diamonds will luminesce under pressure. The phosphorescent quality of diamonds when heated by sunlight is usually believed to have been first revealed by Albertus Magnus (c.
Both diamonds and white topaz may phosphoresce if heated below red heat. Most diamonds are triboluminescent if rubbed with a cloth, and a few are photoluminescent after exposure to direct sunlight. The American geologist Sydney Hobart Ball, who wrote an article on "Luminous Gems, Mythical and Real", outlined the history of discoveries about luminescent and phosphorescent minerals. Thermoluminescence re-emits previously absorbed electromagnetic radiation upon being heated (e.g., thermoluminescence dating). Triboluminescence generates light through the breaking of chemical bonds in a material when it is rubbed, pulled apart, scratched, or crushed. Two types of luminescent phenomena are relevant to crystalline materials. When the energy comes from light or other electromagnetic radiation, it is referred to as photoluminescence which is divisible between fluorescence when the glow ceases immediately with the excitation and phosphorescence when the glow continues beyond the period of excitation. Luminescence is caused by the absorption of energy that is released in small amounts. Luminescence is spontaneous emission of light by a substance not resulting from heat, as distinguished from incandescence, which is light emitted by a substance as a result of heating. Note that the following discussion will omit modern techniques such as X-rays and ultraviolet light that are too recent to have influenced folklore about luminous gems. Triboluminescence from rubbing together two quartz crystals.įirst, it will be useful to introduce some mineralogical terminology for gemstones that can glow when exposed to light, friction, or heat.
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