Etymology From Middle English dyamaunt, from Old French diamant, from Late Latin diamās, from Latin adamās, from Ancient Greek ἀδάμᾱς (adámās, “diamond”). Doublet of adamant. The printing sense is a calque of Dutch diamant, used by Dirck Voskens who first cut it around 1700; compare pearl, ruby (“size of type between pearl and nonpareil”).
A glimmering glass-like mineral that is an allotrope of carbon in which each atom is surrounded by four others in the form of a tetrahedron.
The saw is coated with diamond.
synthetic diamond
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A gemstone made from this mineral.
The dozen loose diamonds sparkled in the light.
Although there are dozens of different types of gems, among the best known and most important are diamond, ruby and sapphire, emerald and other gem forms of the mineral beryl, chrysoberyl, tanzanite, tsavorite, topaz and jade.2012 March 23, Lee A. Groat, “Gemstones”, in American Scientist, volume 100, number 2, archived from the original on 14 Jun 2012, page 128:
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she is wearing small diamond studs in her earlobes. the kind u wear if u’re a modest person & u don’t want to wear anything that could catch on stuff, or be a health risk in a hospital – but u’re still someone who cares.2017, Nick Lake, Satellite, London: Hodder Children’s Books, →ISBN, page 259:
Elphingston. Pearl a Chevron Diamond between three Boars Heads Eraz'd Ruby, arm'd of the first. / Eymouth. Diamond a Lyon Rampant Pearl, on a Canton of the 2d, a Cross Ruby.1720, Francis Nichols, Rudiments of Honour, page 296:
The Field is Ruby, on a Bend Topaz, three Martlets Diamond. The Armes of the most Noble and Puissant Lord, Edward Brabazon, Earl of Meath, and Baron of Atherdee in the Kingdom of Ireland. His Lordship's Atchievements are Quarterly of sixteen Coats. 1. Brabazon, as above. 2. Diamond, on a Chevron between three Pickaxes Pearl, as many Mullets Ruby, by the Name of Mosley. 3. Saphire, ten Bezants, 4, 3, 2, 1, by the Bisset.1726, John Guillim, The Banner Display'd; Or, an Abridgment of Guillim, page 504:
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Pearl, an Eagle, Diamond, between three Crosses Patee, Ruby, for Morrys.1754, John Lodge, The Peerage of Ireland; Or, a Genealogical History of the ..., page 71:
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Something that resembles a diamond.
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Geometry, Mathematics, Sciences A rhombus, especially when oriented so that its longer axis is vertical.
An adder writhes out of the bush, I can see the diamonds on its back; it shrithes across the sandy soil, and bites the right foot of one of the knights.2003, Kevin Crossley-Holland, “The Most Bitter Day”, in King of the Middle March (Arthur; 3), London: Orion Children's Books, →ISBN; 1st American edition, New York, N.Y.: Arthur A. Levine Books, Scholastic Inc., October 2004, →ISBN, page 349:
Etymology From Middle English dyamaunt, from Old French diamant, from Late Latin diamās, from Latin adamās, from Ancient Greek ἀδάμᾱς (adámās, “diamond”). Doublet of adamant. The printing sense is a calque of Dutch diamant, used by Dirck Voskens who first cut it around 1700; compare pearl, ruby (“size of type between pearl and nonpareil”).
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Made of, or containing diamond, a diamond or diamonds.
He gave her diamond earrings.
But in the diamond jubilee state coach – this one comes with both suspension and air conditioning – the queen’s hands were folded calmly in her lap.2023 May 6, Rachel Cooke, “It was ludicrous but also magnificent: the coronation stirred every emotion”, in The Guardian, archived from the original on 15 Jul 2023:
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Of, relating to, or being a sixtieth anniversary.
Today is their diamond wedding anniversary.
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Of, relating to, or being a seventy-fifth anniversary.
Etymology From Middle English dyamaunt, from Old French diamant, from Late Latin diamās, from Latin adamās, from Ancient Greek ἀδάμᾱς (adámās, “diamond”). Doublet of adamant. The printing sense is a calque of Dutch diamant, used by Dirck Voskens who first cut it around 1700; compare pearl, ruby (“size of type between pearl and nonpareil”).