The priceless 'Sefadu Diamond', is the world's largest rough uncut diamond. Discovered in 1970 near the town of Sefadu in Sierra Leone, the diamond weighs 620 carats and measures 2.75 inches from tip to tip. By contrast, the average diamond ring weighs one-third of a carat, even the famous Hope Diamond pales in comparison, weighing a mere 44 carats.

This rare diamond is owned by lazare Diamonds of USA, who have kept it in its natural, uncut state.

A NEW coloured gemstone, christened Mandarin Garnet, is wining interest among the international buying community.

The stone, which is mined exclusively in Namibia, is pure spessartine garnet and an intense orange in colour.

Initially named Hollandine, in honour of the Dutch royal House of Orange, Mandarin Garnet is available in any size and shape up to 10 carats. It has a hardness of 7.4-7.5, a specific gravity close to 4.1 and refractive index of about 1.8.

The stone "displays an intense orange colour that is particularly brilliant on winter days or in the evening when the light is strong".