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Tag: semi-precious stones

Gemstones – Gateway to the Earth

Objects of desire. Wonders of nature. Healing stones. Precious gems. Big clunkers. Gemstones may be called many names but often very little is known about their origin, mining and processing. Journalist Petra Springer frequently accompanied her Brazilian geologist husband on his travels and was able to have a look behind the scenes. She says: “The saying I liked best was ‘stones are the gateway to the earth'”. Quality check and finish In their original form, precious stones are minerals or rocks, raw and shapeless when first mined. Classification characteristics of the more than one hundred types of gemstones are transparency, purity, color intensity and rarity value. In addition, they must have a Mohs hardness (relative hardness value of minerals, named after the German mineralogist Friedrich Mohs) higher than 7. To create a gemstone with perfect luster and optimal refraction, the cutter will grind away at least 50 percent of the rough stone. It is often the cut that makes a gem particularly valuable. The art of cutting means shaping each individual gemstone so that the incident light on the stone is refracted in the most optimal way, thereby enhancing the colour intensity. Gemstones that do not meet the above criteria or have a lower degree of hardness are called semi-precious stones. Among these are agate, amethyst or rose quartz. In mineralogy and gemology, however, the term “semi-precious stone” is no longer used. One speaks of gemstones or precious stones. Places of discovery – finding stones During numerous business trips to Brazil with my husband, a geologist and gemologist, I have had the opportunity to experience the gemstone trade first-hand at discovery sites, in mines, with local middlemen or in the search for new Garimpeiros. “Garimpos” is the Brazilian word for small-scale mining which means the search for raw stones by hand. Even today, the discovery of a gemstone is not an everyday occurrence – a lot of good luck is involved. After mining, the stones are taken to smaller intermediate trade centers near the sites where they were found. What may look like a market is a place where gemstones are traded with wholesalers and middlemen. Stones are offered for sale at stalls or the goods are viewed directly from backpacks. The most valuable stones In addition to Brazil, there are discovery sites all over the world. Sapphires and rubies, which are mainly found in Burma, Thailand, Sri Lanka and India, are among the most valuable of all gemstones.… weiterlesen