Etymology From the manner of preparing indigo practiced in the Ottoman Empire ("Turkey"). Doublet of turquoise blue.
1
Obsolete A deep blue obtained by careful application of indigo dye to silk.
Silk is dyed blue with indigo alone, without any proportion of woad... with ſix pounds of bran, and about twelve ounces of madder... half a pound of madder for each pound of potaſh, renders the vat greener, and produces a more fixed colour in the ſilk... it is wrung out, and expoſed to the air, that the green colour may change to a blue... Some addition is required to be made to the indigo, to give ſilk a deep blue... For the Turkey blue, which is the deepeſt, a ſtrong bath of archil is firſt prepared. Conchineal is alſo ſometimes uſed, inftead of archil, for the ground, to render the colour more permanent.1810, "Dyeing", Encyclopaedia Britannica, 4th ed., Vol. VII, §§300–302
The blues are divided by dyers into five, light blue, sky blue, middle blue, king's blue, Turkey blue. The two last require a previous ground of archil.1815, Thomas Cooper, Practical Treatise on Dyeing and Callicoe Printing..., page 252:
The bales for the Tunis market should be assorted as under... 9 pieces Turkey blues [per] 50 pieces...1818, C.W. Rőrdansz, European Commerce..., page 683: