E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
Di’amond.
A corruption of adamant. So called because the diamond, which cuts other substances, can be cut or polished with no substance but itself. (Greek, a damao, what cannot be subdued. Latin, adamas, gen. adamant-is; French, diamant.)
1
Di’amond (3 syl.). Son of Ag’apë, a fairy. He was very strong, and fought either on foot or horse with a battle-axe. He was slain in single combat by Cam’balo. (See TRIAMOND.) (Spenser: Faërie Queene, book iv.)
2
A diamond of the first water. A man of the highest merit. The colour or lustre of a pearl or diamond is called its “water.” One of the “first water” is one of the best colour and most brilliant lustre. We say also, “A man of the first water.”
3
A rough diamond. An uncultivated genius; a person of excellent parts, but without society manners.
4
“As for Warrington, that rough diamond had not had the polish of a dancing-master, and he did not know how to waltz.”—Thackeray.
Diamond cut diamond. Cunning outwitting cunning; a hard bargain overreached. A diamond is so hard that it can only be ground by diamond dust, or by rubbing one against another.
