蓝宝石

noun

sapphire; a precious gemstone, a variety of corundum

Although 'sapphire' commonly refers to the blue variety in English, in Chinese '蓝宝石' (lánbǎoshí) traditionally denotes blue sapphire, but the definition extends to other colors (except red, which is ruby) and colorless corundum. It is valued for its hardness and used in jewelry and industrial applications like precision bearings. See also entry for '刚玉' (corundum).