Results: Gems from Down Under: The Story of Australian Diamonds ** Part Four Australia is the home of the most prolific diamond mines in the world – the Argyle mine in the East Kimberley region, discovered in 1979. Diamonds in Australia were found as early 1851.

The Argyle mine also produces champagne, cognac, and blue diamonds. Each year, the company holds an exclusive sale of the best pink diamonds recovered from the mine. The event is known as the Argyle Pink Diamonds Tender, and the diamonds for sale are exhibited in major diamond industry centers around the world prior to the auction. Which Diamonds do you prefer?

Diamonds in Australia were recorded in the Bathurst area, New South Wales in 1851. Significant quantities also were mined from alluvial deposits at Copeton and Bingara, near Inverell in north-eastern New South Wales, from 1867 to 1922 and minor production resumed at Copeton in 1997, but has since stopped. Numerous minor occurrences of diamond have been recorded elsewhere in Australia. Creek sediment sampling and other exploration techniques in the early to mid-1970s led to the discovery of 23 diamondiferous but low-grade pipes at Ellendale in 1976 and the Argyle deposit in 1979. Shark cages were used in the late 1980s to protect scuba divers against crocodiles while they sampled diamonds (eroded from land) from the seabed off river mouths in the north-east Kimberley region. Small numbers of gem-quality diamonds have since been recovered using an airlift drill attached to a boat. Would you be willing to mine for diamonds under water in a shark cage?

The Ellendale Diamond contributes around half of the world's supply of fancy yellow diamonds. According to Kimberley's website, Ellendale is one of only three hard-rock diamond mine locations in Australia. Diamonds were first discovered at Ellendale in an olivine lamproite pipe in November 1976. A number of small diamond 'pipes' with a much higher proportion of gem-quality diamond than Argyle have been mined at Merlin in the Northern Territory and Ellendale in the west Kimberley region. Have you ever seen a rough diamond, before it is cut and polished?

Diamond consists of only one element, carbon, although it commonly contains traces of nitrogen. It crystallises in the cubic system. The octahedron is a common form but many mixed forms occur as a result of formation and growth conditions. Twinned crystals (macles) are often seen. Diamonds increase in value with 'whiteness', clarity and size. However, fancy colours, such as blue, green, yellow, orange, pink and red are extremely rare and therefore very valuable. The largest diamond found so far in Australia was mined at the Merlin Mine, Northern Territory, in 2003 and weighed 104.73 carats. Have you ever seen a diamond this big? (Most likely in a Museum.)