Citrine and sapphire gemstones. Fine and poor examples of gem cutting and polishing. At left is a superbly cut citrine (a yellow variety of quartz), w

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Citrine and sapphire gemstones. Fine and poor examples of gem cutting and polishing. At left is a superbly cut citrine (a yellow variety of quartz), while at right is a poorly cut sapphire (blue), a variety of the mineral corundum (aluminium oxide).

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Size: 4747px × 3682px
Photo credit: © NATURAL HISTORY MUSEUM, LONDON/SCIENCE PHOTO LIBRARY / Alamy / Afripics
License: Licensed
Model Released: No

Keywords: arc, artwork, background, black, cut, cut-, cutout, destructive, diagram, earth, geographical, geography, geological, geology, illustration, island, magma, margin, marine, ocean, oceanic, plate, plates, subduction, tectonics, volcanic, volcano, zone