“At the Corundum Hill Mine (near Highlands), various shades of ruby gem corundum have been found,” the U.S. Geological Survey reported in 1906. However, though the gems were similar to the red rubies ...

While analyzing some of the world’s oldest coloured gemstones, researchers from the University of Waterloo discovered carbon residue that was once ancient life, encased in a 2.5 billion-year-old ruby.

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THE three works cited below give much new and valuable information concerning the mode of occurrence, the processes of mining, and the uses of corundum. As the mineral is of growing economic value, ...