Diamond

Diamond is pure carbon, crystallised under the high heat and pressure of the mantle, Mohs hardness 10 — the hardest natural material on earth. But “hardest” does not mean “unbreakable”, nor “most valuable” — of the 4Cs, cut matters most to its beauty. Here is the whole picture, from identity and buying to the truths and care.

About Diamond

Diamond is crystalline carbon, Mohs hardness 10, the hardest natural mineral; but hardness (resisting scratches) and toughness (resisting impact) are two things — it has cleavage and can chip on the right angle. It crystallises under high heat and pressure deep in the mantle. Its colour runs from the common colourless-to-faint-yellow to the rare pink, blue and green “fancy colours”, each with its own cause.

Why Choose a Diamond

Diamond is April’s birthstone, uniting fire, brightness and scintillation, and the most widely chosen stone for engagement and marriage. With the story of “one grain of carbon, formed over billions of years”, it has become a byword for a promise. Hard-wearing and forever bright, it suits daily wear and passing down the generations.

History & Famous Stones

The story of diamond is one of a journey from the rarest of treasures to the reach of many — India’s Golconda was once the world’s only source, until the great South African finds of the 19th century brought diamond from the crowns of kings into everyday hands. The most legendary stones still sit in crowns and museums:

• The Cullinan: unearthed at South Africa’s Premier mine in 1905 at 3,106 carats — the largest gem-quality rough ever found. From it was cut the “Great Star of Africa” (Cullinan I), 530.2 carats, the largest colourless cut diamond in the world, set in the British Sovereign’s Sceptre; Cullinan II (317 carats) sits in the Imperial State Crown.
• The Koh-i-Noor: 105.6 carats, of ancient Indian origin, passed through centuries of conquest — one of the most contested diamonds on earth, now set in the British Queen Mother’s Crown.

The Truth About Diamond

Of the 4Cs (carat / colour / clarity / cut), cut matters most to “is it beautiful to the eye”; clarity is often just “buying a letter”.

• Truth one: cut makes or breaks it. An H-colour diamond with an outstanding cut often beats an F-colour one loosely cut.
• Truth two: clarity is often buying a letter. VS and SI are often indistinguishable to the eye, yet far apart in price.
• Truth three: the certificate must match the stone. Read the girdle laser number — do not settle for the three words “it has a certificate”.
• Truth four: lab-grown and natural diamond cannot be told apart by eye, needing laboratory instruments and the girdle inscription.

Diamond on the Market

Besides natural diamond, there are lab-grown diamonds, moissanite and cubic zirconia (CZ); prices differ enormously, and the keys are the certificate and girdle number.

Type	Traits	Price	How to tell
Natural diamond	Earth-formed, GIA certificate	Highest	Certificate + girdle laser number
Lab-grown diamond	Same composition, laboratory	Low–mid	Girdle inscription “LABORATORY-GROWN”
Moissanite	Silicon carbide, more fire	Low	Dual tester, rainbow flash
Cubic zirconia (CZ)	Glassy, scratches easily	Very low	Low hardness, hazes quickly

Before You Buy

Buying a diamond means “knowing how to read a certificate” (not just having one), looking at it once in daylight, and matching the girdle laser number.

• Know how to read a certificate; if you cannot, bring someone who can.
• Look at it once in daylight — do not be fooled by showroom lighting.
• Confirm the girdle laser number against the certificate.
• Think it through: are you buying a grade letter, or a stone your own eyes truly find beautiful.