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| [547] The Formation of Gem Materials |
The most valuable gems come from crystallized minerals that have formed under heat and pressure deep inside the earth. The perfect order of the crystal structure is what makes gemstones transparent yet durable. Crystallization of minerals is a fairly slow process, to enable it to occur, specific geologic and chemical conditions must be met. Depending on the conditions, the same chemical recipe will crystallize in different crystal structures....
(1999)
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| Releated Categories: [Gemology]|[Handbook for the Gem Buyer] |
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| [548] The Four C's Plus One |
The valuation of a gemstone is derived from the "FOUR C's": carat, color, clarity, and cut. Understanding all four of these is vital background to the buyer. If you are buying an expensive stone with a price in four figures or more, buy it loose so you can see it weighed and be able to fully examine it. Of course, this will not always be possible; some jewelry is already set, for example, if you were buying a piece of jewelry from an estate or from an auction. Some gemstones are mounted in a bezel or other setting that would be damaged upon removal.... (1999)
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| [545] The Joy of Gems |
Gemstones have been treasured by humankind since the beginnings of civilization. Every ancient civilization found practical and decorative purposes for gem materials. The durability of gemstones lent itself to practical uses: ancient gemstones were carved and used as seals that acted as the bearer's signature. Egyptian scarabs are the best known of ancient seals; the Egyptian chief justice wore a lapis lazuli seal engraved with the image of the god Ma which represented "Truth". Scarabs were also said to have the power to deliver the dead into eternal life. Of course, these gemstone seals were beautiful so they were also worn as talismans to protect and bless the wearer. The crown jewels of many kingdoms were pawned to finance wars of conquest and discovery; the best known was Queen Isabella of Spain who financed Christopher Columbus in his voyages. Fortunately, today everyone can enjoy gemstones.... (1999)
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| [549] The Treatment of Gemstones |
The treatment and enhancement of gemstones has existed for centuries. Some enhancements improve on nature slightly, are undetectable, and they are permanent; this provides the gem market with a larger supply of beautiful gemstones. Other treatments produce dramatic changes in the gemstone; the irradiation and heating of colorless topaz that permanently transforms it into blue topaz is an excellent example. A few treatments are less stable and should be avoided by the knowledgeable buyer..... (1999)
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| Releated Categories: [Gemology]|[Gemstone Treatments]|[Handbook for the Gem Buyer] |
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| [567] Topaz |
Topaz is a gem that is very often eye clean, so stones with good clarity are available. The red color can be a strawberry hue: these are quite hard to find and will command the highest price. Deep pinks can be exceptionally beautiful. Pink topaz is mined in Pakistan. Pink stones are also available from Brazil; but most of these stones have been heated from orange material. It will not be easy to find the red and deep pink colors; if the color is intense, expect to pay an expensive price per carat. Pastel pinks are also available. These rarer topaz colors generally are found in stones under ten carat sizes.... (1999)
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