"Few words enter more largely into the composition of slang, and colloquialisms bordering on slang, than does the word BLUE. Expressive alike of the utmost contempt, as of all that men hold dearest and love best, its manifold combinations, in ever varying shades of meaning, greet the philologist at every turn." [John S. Farmer, "Slang and Its Analogues Past and Present," 1890, p.252]
The color of constancy since Chaucer at least, but apparently for no deeper reason than the rhyme in true blue (c.1500). From early times blue was the distinctive color of the dress of servants, which may be the reason police uniforms are blue, a tradition Farmer dates to Elizabethan times. For blue ribbon see cordon bleu under cordon. Many IE languages seem to have had a word to describe the color of the sea, encompasing blue and green and gray; e.g. Ir. glass (see Chloe); O.E. hæwen "blue, gray," related to har (see hoar); Serbo-Cr. sinji "gray-blue, sea-green;" Lith. yvas, Rus. sivyj "gray.""In early examples the word, like most other names of precious stones, is of vague meaning; the mediæval references to the stone are often based upon the descriptions given by classical writers of the smaragdus, the identity of which with our emerald is doubtful." [OED]
"[I]n med.L. spiced drink, hence spice, pepper (generally), Sp. pimiento, Fr. piment are applied to Cayenne or Guinea pepper, capsicum; in Eng. the name has passed to allspice or Jamaica pepper. [OED]The piece of red sweet pepper stuffed in a pitted olive so called from 1918, earlier pimiento (1901), from Sp."[G]rasse wydowes ... be yet as seuerall as a barbours chayre and neuer take but one at onys." [More, 1528]
"Do not do unto others as you would that they should do unto you. Their tastes may not be the same." [George Bernard Shaw, 1898]