Reference work entry
Ruby is red corundum. Its chemical composition is aluminium sesquioxide (Al 2O 3). Its red or pink colour stems from the trace element chromium (Cr 3+). Rubies with a high degree of transparency and a blood red colour, especially the so-called ‘pigeon blood red’ type, are considered the most valuable and are sometimes more expensive than a diamond of similar size. Rubies form in some magmatic rocks and metamorphic rocks and are also found in the gravel layers of rivers. The main production areas include Myanmar, Sri Lanka, Thailand and Australia. Rubies are also mined in Fujian, Hainan and Taiwan Provinces in China (Fig. 24).
© Springer Nature Singapore Pte Ltd. 2020