ruby, precious stone, the transparent red variety of corundum, found chiefly in Myanmar, Thailand, and Sri Lanka and classified among the most valuable of gems. The Myanmarese stones are blood red, the most valued tint being the "pigeon's blood." The Thai stones are darker and the Sri Lankan stones lighter than the Myanmarese specimens. Star rubies, i.e., those that show an internal star-shaped formation when cut in cabochon (with a rounded top), are rare. Synthetic rubies are manufactured by the fusion of pure aluminum oxide. Chromium oxide is added to provide the appropriate color.

ruby a precious stone consisting of corundum in colour varieties varying from deep crimson or purple to pale rose (the term pigeon's blood is sometimes used of ruby of a particularly deep shade).

The name may also be used for the less valuable spinel ruby, a deep red variety of the mineral spinel. The ruby may also be taken as the type of something exceedingly precious, as in the biblical passage.
ruby wedding the fortieth (or occasionally, the forty-fifth) anniversary of a wedding; the name is recorded from the early 20th century.

ru·by / ˈroōbē/ • n. (pl. -bies) a precious stone consisting of corundum in color varieties varying from deep crimson or purple to pale rose. ∎  an intense purplish-red color. ∎ Printing an old type size equal to 5¹/₂ points (smaller than nonpareil and larger than pearl).

ruby Gem variety of the mineral corundum (aluminium oxide), whose characteristic red colour is due to impurities of chromium and iron oxides. The traditional source of rubies is Burma. Today, synthetic rubies are widely used in industry.

ruby XIV. — OF. rubi (mod. rubis) — medL. rubīnus, sb. use of adj. f. base of L. rubeus, ruber RED.

ruby See CORUNDUM; and SPINEL.

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