What it is confused with
Cubic zirconia, moissanite, white sapphire and glass. Moissanite shows doubled facet edges under a loupe and can fool simple heat testers, so a laboratory report is the reliable check.
Colorless, also yellow, brown, blue, pink
Diamond birthstone
Diamond, the birthstone for April, is pure carbon (C) in cubic crystal structure, colorless, also yellow, brown, blue, pink, rated 10 on the Mohs scale. Traditionally, it is associated with clarity, permanence and commitment — attributed, not demonstrated.
- Mohs hardness
- 10 scratches window glass
- Crystal system
- Cubic C
- Pliny, AD 77
- Book 37.15 as “adamas”
- Main sources today
- Botswana also Russia, Canada
Pliny, Natural History, tr. Bostock and Riley.
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Properties
Composition
Pure carbon (C) in cubic crystal structure
Hardness (Mohs)
10
Crystal system
Cubic
Color
Colorless, also yellow, brown, blue, pink
Mined in
Botswana, Russia, Canada, South Africa, Australia
Worth knowing
The hardest natural substance — but hardness is not toughness. A diamond will scratch anything, and still cleave if struck along its grain.
History
First mined in India before 400 BCE; the word comes from the Greek adamas, 'unconquerable'.
Buying
Buying Diamond: fakes, value and treatments
What decides the price
Price follows the four Cs — cut, color, clarity and carat weight. Laboratory-grown diamonds are chemically identical and much cheaper, which is why a grading report stating origin matters.
Where it is used
By weight, most mined diamond goes to industry for cutting, drilling and polishing tools.
A less familiar fact
The largest gem-quality rough diamond ever found, the Cullinan, weighed 3,106 carats when it was discovered in South Africa in 1905.
Practical
Caring for Diamond
How to clean it
Soapy water and a soft brush — diamond attracts grease and loses sparkle fast. Safe in ultrasonic.
How to tell it is real
The fog test is the quick one: breathe on it. Diamond clears almost instantly while cubic zirconia stays fogged a second longer; moissanite clears nearly as fast as diamond, so the fog test alone will not catch it. Moissanite also shows doubled facet edges under magnification.
How hard is Diamond?
Diamond is the hardest natural material, but hardness is not toughness: a sharp blow along one of its four cleavage directions can chip it. Day to day, grease dulls the sparkle long before anything could scratch it. No stone in this reference is harder; the runner-up is Ruby (9).
Diamond, at 10, is the hardest of the 43 stones here.
Primary source
What Pliny the Elder wrote about Diamond
“The substance that possesses the greatest value, not only among the precious stones, but of all human possessions, is adamas; a mineral which, for a long time, was known to kings only, and to very few of them.”
“These stones are tested upon the anvil, and will resist the blow to such an extent, as to make the iron rebound and the very anvil split asunder.”
Pliny the Elder, The Natural History, translated by John Bostock and H. T. Riley (London: H. G. Bohn, 1855–57), book 37, chapter 15 — read the original text.
Pliny lists six kinds of adamas, and not all of them can have been diamond, but his Indian adamas — “two cones united at the base” — is the octahedral diamond crystal. The anvil test is false: diamond is the hardest mineral, yet it is brittle along its cleavage planes, and a hammer blow can shatter it. Who Pliny was and why we quote him →
Traditional associations
Diamond is traditionally associated with clarity, permanence and commitment. Chakra in crystal practice: Crown. Element: Fire.
Questions about Diamond
What is Diamond made of?
Pure carbon (C) in cubic crystal structure, crystallizing in the cubic system.
Which month is Diamond the birthstone for?
April.
Where does Diamond come from?
Botswana, Russia, Canada, South Africa, Australia.
Can Diamond be worn every day?
Yes. It rates 10 on the Mohs scale, and the main thing to watch is a sharp blow along its cleavage, and grease, which kills the sparkle.
Sources
Statements of fact on this page were checked against these sources in October 2026. How we choose and check sources: editorial policy.
Cite this page
AstroHot. “Diamond Birthstone: The April Stone — Meaning and Properties.” Accessed October 28, 2026. https://astrohot.com/crystals/gemstones/diamond/
For Wikipedia
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