Gemmological facts

Species

Carbon (diamond)

Hardness (Mohs)

10

Family

Precious stone

Signature colour

Colourless

Selection criteria

The 4Cs: carat, colour, clarity, cut

• Mineral species: Pure crystallised carbon (cubic system)
• Hardness: 10 on the Mohs scale, the maximum. Note however that diamond is cleavable: its edges remain sensitive to hard knocks.
• Colours: From colourless to faintly yellow along the D-to-Z scale, plus fancy colours: yellow, brown (cognac), pink, blue, green and black.

Main origins

• Botswana

  The world's leading source by value, with fine-quality stones.

• Russia (Yakutia)

  Very high-volume deposits, mined in an extreme climate.

• Canada

  Recent and highly traceable production, often bright stones.

• South Africa

  Birthplace of the modern industry (Kimberley).

• Namibia

  Marine and alluvial deposits, stones naturally sorted by the sea.

• Australia (Argyle)

  Historic reference for pink diamonds; the mine is now closed.

Best-suited cuts

• Round brilliant

  57 or 58 facets: maximum brilliance, the most requested cut.

• Princess

  Square and lively, with a good yield from the rough.

• Oval

  Elongates the finger and looks larger at equal weight.

• Cushion

  Broader flashes of fire, soft and vintage in feel.

• Emerald (step cut)

  Hall-of-mirrors effect: demands very good clarity.

• Pear

  Elegant as a pendant as well as in a ring.

• Marquise

  Tapered silhouette with excellent visual spread.

• Heart

  A symbolic choice, best kept for stones of one carat and above.

• Baguette

  Ideal as side stones flanking the centre gem.

Jewellery and care

Engagement solitaire, full and half eternity bands, pavé, halo settings, pendant, earrings and tennis bracelet: its hardness allows daily wear.

Lukewarm soapy water and a soft brush are enough to restore the sparkle. Have the setting checked once a year, and avoid steam or ultrasonic cleaning on treated or heavily included stones.