Ruby
Precious stone
Ruby is the red variety of corundum, coloured by chromium. As hard as sapphire, it combines intense colour with the durability required for daily wear; the finest slightly purplish reds are known as « pigeon blood ».
Gemmological facts
- Species
- Corundum
- Hardness (Mohs)
- 9
- Family
- Precious stone
- Signature colour
- Red
- Mineral species: Corundum (aluminium oxide, Al₂O₃)
- Hardness: 9 on the Mohs scale — only diamond is harder.
- Colours: From pinkish red to deep purplish red; the vivid, slightly purplish « pigeon blood » red is the most sought after. Natural chromium fluorescence heightens the glow.
Main origins
Burma (Mogok, Myanmar)
The historic benchmark for pigeon-blood red.
Mozambique (Montepuez)
Major contemporary source, saturated reds and clean stones.
Thailand / Cambodia
Darker reds with brownish or garnet nuances.
Sri Lanka (Ceylon)
Light to pinkish reds, very luminous.
Madagascar
Recent deposits, a wide range of hues.
Tanzania (Winza, Songea)
Vivid reds, often in smaller sizes.
Best-suited cuts
Oval
The most common cut: it preserves weight and colour.
Cushion
A high-jewellery classic that concentrates the red at the centre.
Round brilliant
Maximum brilliance, ideal for halos and smaller stones.
Pear
Elegant for pendants and drop earrings.
Heart
A symbolic choice, best kept for well-saturated stones.
Cabochon
Essential for star rubies (asterism).
Jewellery and care
Alternative engagement ring, diamond-halo solitaire, set wedding band, pendant, earrings and bracelet: hardness 9 allows daily wear.
Lukewarm soapy water and a soft brush. Fissured or glass-filled rubies must avoid ultrasonic cleaning, steam and heat; have the setting checked once a year.