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Gemstones are minerals, when cut and polished demonstrate: Beauty, Rarity, Durability, Size Beauty • Translucent (see through) • Even color throughout is most prized • Market colors are blue, red, yellow, and green • Exception is a colorless diamond, with “brilliance” (can reflect many colors) www.pbs.org/.../diamond/images/gp06emerald.jpg Durability • Related to hardness, ability to resist scratching • Level 7 on Moh’s Scale (quartz is a 7) • Opal is a soft gem – a mineraloid • Displays “fire” or variety of brilliant colors. http://www.mineralminers.com/images/sapphire-blue/gems/sblg136.jpg Rarity • Uncommon, very few found • Large, Unique color • Very few impurities 287.42 carats and is considered to be one of the largest yellow diamonds in the world. Yellow diamonds are extremely rare http://www.mineralminers.com/images/ruby/gems/rbyg111.jpg . Size (portability) • The stone represents a high concentration of value in a small object, permitting the owner to transport great wealth with relative ease. • Often the choice for ellicit trade. What to look for in a Gemstone: Color • The more pure and vivid the color, the more valuable • even and translucent The Hope Diamond Cut The cut determines the brillance Of the gemstone Clarity- addition of other color or rock fragments The Logan Sapphire Brooch 423 carats Carat – approx. 0.2 grams or 1/5 of a gram 530.20 carats The Star of Africa, a stunning pear shaped diamond Precious or Semiprecious? Precious – a gem must have all 4 of the following qualities: • • • • • Beauty Durability Size Rarity Examples: Diamonds, Rubies, Sapphires, and Emeralds • Pearls and Opals are sometimes included though they are not minerals Semiprecious • Has only one or two of the characteristics of precious stones • Examples: Topaz, Garnet, Peridot, Amethyst, Classifications – most common • • • • Diamond – family is diamond – all carbon Ruby – family is corundum- Al2O3 with Fe Sapphire – family is corundum- Al2O3 with Cr Emeralds – family is beryl- B,Al,Si,O green blue color, also aquamarine, jade • Quartz – family is quartz – SiO4 with other elements • Opals, turquoise, lapis lazuli • Organics – pearls, coral, amber Is it REAL? Natural • Formed in nature • has flaws, often a part of their beauty • REAL Synthetic • Made in lab • Composition the same • No (or very few) flaws (inclusion) • Difficult to identify(leave to the professionals) • REAL Imitations •Not same Composition •Only “looks” the same •Plastic or glass usually •NOT REAL Diamonds • • • • • Found in kimberlite – type of volcanic rock Extreme temperature and pressure Largest selling gemstone – MARKETING Anyone can own one, not very expensive Mined mostly in sub-Saharan Africa and Australia • Cut in Europe and Israel Diamond Costs • Environmentally – many are not mined using environmentally friendly methods or with safety for the miners a consideration • Politically – to fund para-military groups or insurgents against govt.s • Illicit trade – easy to smuggle – “blood diamonds” http://www.fotosearch.com/thumb/IMP/IMP182/1525R-80643.jpg