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Cut and polished diamond
Diamond. Macrophotograph of a cut diamond. The colours result from a filter, used to simulate the exceptional light dispersion. Diamond is an allotrope of carbon, having an isometric octahedral lattice structure. It is the hardest known mineral. It is found in ultramafic rocks, especially kimberlite breccias, and in detrital sedimentary deposits. Large crystals are mined for use as gemstones. Small crystals are used as an industrial abrasive. Most diamond is colourless, but some forms may have yellow, brown, grey or green tints. Most forms are fluorescent in ultraviolet light. Splendid crystals are found in South Africa, Russia, Brazil and Sierra Leone.
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