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How are rubies and sapphires made?

[ad_1] Rubies and sapphires are varieties of corundum, a common mineral that can be transparent and used as a gemstone. Synthetic production of corundum began in 1837, with the Verneuil process introduced in 1903 for mass production of flawless rubies and sapphires. The process involves melting highly purified alumina powder using a blowtorch and accumulating […]