Gemstones Week of 2 23
Gemstones Week of 2 23 1108
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This 3 page Class Notes was uploaded by Caroline Bacevice on Friday February 27, 2015. The Class Notes belongs to 1108 at Ohio State University taught by Loren Babcock in Spring2015. Since its upload, it has received 40 views. For similar materials see Gemstones in Earth Sciences at Ohio State University.
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Date Created: 02/27/15
Gemstones Week of 223 What determines the value of a diamond Cut Faceted to maximize the brilliance and re of a gem o Poorly cut stone has poorly chosen proportions poor brilliance poor re light leakage from pavilion misplaced facets extra facets etc o A Natural an extra face that represents a polished extra face of a crystal Facets o Tble men Girdle PavHHon Culet 0000 Diamond Grading o Brilliant Cut 0 Color determined by grading visual comparison with knowns or instrumental means 0 Increasing yellow content decreasing value Fancy colored stones 0 Large pink diamonds rare and expensive 0 Natural blue diamonds contain boron natural yellow diamonds contain nitrogen Standards 0 International standard 1970 RAL 560 ASE o Gemological Institute of America GIA 0 International Diamond Council IDC Clarity o Clarity decreased by aws or blemishes o Scratches o Inclusions minerals liquids gasses contained in the stone 0 Carat weight 0 1 carat 02 g o 1 carat 100 points Treatment of Diamonds 0 Filling of cracks Cracks that reach the surface are lled with glasslike material 0 ID Optical microscope examination greasy appearance ash effect bubbles Drilling of inclusions by laser Solutions poured into inclusions to bleach them Irradiation Used to change the color 0 ID Irradiation only changes the surface of the stone and produce a concentration of color where the gem is thin Diamond Synthesis 0 Can be grown by high pressure high temperature techniques or by chemical vapor deposition Industrial Diamonds 0 Bort Poorly crystallized black gray or brown translucent to opaque Ballas spherical aggregates of many small diamond crystals Carbonado Opaque black or gray tough and compact o Meteorites 0 Synthetic Diamonds Industrial Purposes for diamonds Polishing grit for polishing diamonds and other gems Dental drills and other drills Saw blades Synthetics semiconductors microchips Some famous diamonds Cullinan I Star of Africa 53220 carats 0 One of 105 cut from one of the largest rough gem diamonds 0 Now in English Sovereign s Scepters Cullinan ll 31240 carats 0 Now in English Imperial State Crown 0 Both are held in the Tower of London KohiNoor 10892 diamonds 0 quotMountain of Lightquot 0 Originally a round stone 186 carats o Belonged to the Indian Raj later plundered by the Shah of Persia o Obtained by the British East India Company then presented to Queen Victoria 1850 0 Now in the crown of Queen Elizabeth The Queen Mother VictoriaTransvaal Diamond 18450 carats 0 Featured in a Tarzan movie 0 Now in the Smithsonian Institution MarieAntoinette39s diamond earrings 2034 carats 1425 carats 0 Gift of Louis XVI o Disappeared during the French Revolution 1792 0 Later appeared in Russia Sold to Pierre Cartier 1928 then sold to Marjorie Meriwether Post Napoleon Necklace given to Emperes Diamonds in both sets from India Brazil Both now in the Smithsonian Institutions US National Museum Hope Diamond 0 Now in the Smithsonian Institution Viewed by more than gt6 million visitors annually Probably the most sought out object in any museum in the world 0 Why Now the world s largest diamond 4552 carats Largest cut diamond Golden Jubilee owned by the King of Thailand It s deeply colored doesn t seem like a typical diamond o It is the largest known deep blue diamond Blue color one of the rarest colors of fancy colored diamonds Due to substitutions of Boron for carbon 1 B atom per 1000000 C atoms 0 History gt300 years of mystery and intrigue o Discovered in India 0 1668 JeanBaptiste Tavernier French gem merchant sold a 1105 carat blue diamond from India to King Louis XIV of France Cut in Indian stylenatural crystal faces were polished size emphasized over brilliance o 1673 King Louis XIV had stone recut to heart shape improving brilliance reducing size to 6903 carats o 1749 King Louis XV had the stone now called French Blue set in a piece of ceremonial jewelry Order of the Golden Fleece worn by the Queen
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