|Frank Smith Mine|
|Written by Administrator|
|Wednesday, 19 September 2007|
Fraunhofer lines. A group of dark lines (absorption bands) crossing the solar spectrum resulting from absorption of light by the vapor of elements in the sun's chromosphere. Named for their discoverer, Joseph Fraunhofer, in the 19th century, who designated the principal lines by letters of the alphabet. The important lines are given in Angstrom units: A, 7606; B, 6870; C, 6563; D, 5893; E, 5270; F, 4861; G, 4308; H, 3969. The dispersion, i.e., the difference in refractive index of diamond, is measured between the B and G Fraunhofer lines. See dispersion.
French Blue Diamond. The French Blue was a 69.03-carat diamond that was believed by gem historians and now corroborated by H. Tillander, in his study of "The Hope Diamond
and Its Lineage" (1975), to have resulted from the cutting of the 110.50-carat Tavernier Blue. Taver-nier, the noted French jeweler and traveler, reportedly first saw the diamond in India in 1642 and later brought it to France. He sold the stone to Louis XIV and, later, Pitau, the Crown Jeweler of the King, recut it to a 69.03-carat "heart shape." It was once the center stone in the Flame of a Golden Fleece. In 1791 it entered the inventory of the Crown Jewels in the French Royal Treasury (Garde Meuble) where it. remained until the great gem robbery of September 17, 1792. Because of its peculiar blue color, some gem historians once believed that it was perhaps recut again, producing the world-famous Hope and the Brunswick Blue. However, their combined weights are too close to that of the French Blue to make this plausible. Tillander's recent study indicates that the Hope Diamond originated from the French Blue and that the Brunswick Blue must have come from another source. Also known as Blue Diamond of the Crown. See hope diamond, tavernier blue
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