The cutting and polishing of diamonds are very delicate many varieties of glass beads.
Today we know that Zimbabwe was inhabited around 1000 B.C. and was only one of about 2000 such centres scattered through the country called Zimbabwe.
All gems are cut and polished by progressive abrasion using finer and finer grits of harder substances. Diamond, the hardest naturally occurring substance, has a Mohs hardness of 10 and is used as an abrasive to cut and polish a wide variety of materials, including diamond itself. Silicon carbide, a manmade compound of silicon and carbon with a Mohs hardness of 9.5, is also widely used for cutting softer gemstones. Other compounds, such as cerium oxide, tin oxide, chromium oxide, and aluminum oxide, are frequently used in polishing gemstones.
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