the metallic sheen of a mallard ducks blue speculum
In Nature, colour may be a source of great beauty to the beholder, but to a plant or an animal it is most often a means of survival. . . . Natural colour arises from a diversity of mechanisms, often associated with distinct functions. Dyes and stains are used by many creatures, frequently for camouflage. Structural colourtypified by the metallic sheen of a Mallard ducks blue speculumis generally used for the intense colours that announce the presence of an individual, as for example in a mating display. Colour can also be used for warning, as in the poisonous fire-bellied toad, or even for mimicry. Less commonly, animals can dispense with colour altogether and become transparent, or, as in the squid, they can actively control skin colour for the purpose of camouflage, or for attraction and mating.
—Trevor Lamb and Janine Bourriau, from the introduction to Colour: Art & Science, edited by Trevor Lamb and Janine Bourriau, 1995.
bioluminescence.
Some animals give off bioluminescence. Some contain bacteria, which they stimulate chemically to glow, and some use filters to modify this light. Others produce their own alchemy of compounds, which when allowed to mix give off light. . . . Some bioluminescence has a sexual function. Fireflies certainly atract mates with their light displays, and several species of deep-sea squid and fish would appear to use bioluminescence in their courtship displays.
—Peter Parks, from the essay Colour in Nature, from Colour: Art & Science edited by Trevor Lamb and Janine Bourriau, 1995.
once in a blue moon
Blue is always different from yellow, for example: depressed (the blues), where yellow is gay, loyal (true-blue), where yellow is cowardly, and the like. Blue has a similar meaning to yellow about once in a blue moon.
—Marshall Sahlins, quoted by John Gage in the essay Colour and Culture, from Colour: Art & Science edited by Trevor Lamb and Janine Bourriau, 1995.
acira.
A Sanskrit word for diamond, meaning fire or sun.
—The Book of Diamonds by Joan Dickinson, 1965.
arkansas.
The only state in the U.S. where diamonds of any amount have been found. . . . Altogether four pipes have been found, the principal one being called the Crater of Diamonds in which the public may search for a fee.
—The Book of Diamonds by Joan Dickinson, 1965.
arkansas diamond.
Watch out! This is usually rock crystal from Arkansas.
—The Book of Diamonds by Joan Dickinson, 1965.
black diamond.
A dark grey or black diamondperhaps opaque, perhaps semi-transparent. The words are also used to describe carbonado, a tough industrial diamond.
—The Book of Diamonds by Joan Dickinson, 1965.
blue diamond.
Can be any shade of blue but diamonds that are blue in both daylight and incandescent light are rare; most show blue only in daylight. . . . The most famous blue is the Tavernier Blue or the French Blue, from which was cut the Hope Diamond.
—The Book of Diamonds, by Joan Dickinson, 1965.
brown diamond.
A reddish or coffee-brown fancy diamond, second in value among the fancies to yellow.
—The Book of Diamonds, by Joan Dickinson, 1965.
carbonado.
The toughest form of industrial diamond, usually black or gray and principally found in Brazil.
—The Book of Diamonds, by Joan Dickinson, 1965.