Definition of "turquoise"

Although there are dozens of different types of gems, among the best known and most important are […] . (Common gem materials not addressed in this article include amber, amethyst, chalcedony, garnet, lazurite, malachite, opals, peridot, rhodonite, spinel, tourmaline, turquoise and zircon.)

2012 March, Lee A. Groat, “Gemstones”, in American Scientist‎, volume 100, number 2, archived from the original on 14 June 2012, page 128

The half-dozen pieces […] were painted white and carved with festoons of flowers, birds and cupids. To display them the walls had been tinted a vivid blue which had now faded, but the carpet, which had evidently been stored and recently relaid, retained its original turquoise.

1963, Margery Allingham, chapter 1, in The China Governess‎