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In addition, it must be hard and durable. Its value increases if it is also rare.The beauty of a gem is measured in terms of its clarity, brilliance, and color. Comments
To be classified as a mineral, a material must possess the following characteristics: 1  Natural occurrence: it must occur naturally and hence should not be man-made. 2  Crystalline solid substance: should have a well-defined crystalline structure and should be a solid substance. 3  Inorganic origin: should not contain carbon.