Specifically,
"The Argyle diamond story has its origins in the early 1970s, when one of the world's most significant find of diamonds was made at Smoke Creek in the remote north of Western Australia, over 2000 kilometres from Perth, the state capital."
You can read more about the diamond mining industry in Australia, below.
Australia produces brown diamonds from their mines.
Natural diamonds are mined throughout the world, including in Australia.
Industrial diamonds come from diamond mines, in fact about 75% of all diamonds mined are industrial diamonds.
Most of the world's gold comes from mines in China, Australia, Russia, and the United States. On the other hand, the majority of the world's diamonds are sourced from countries such as Russia, Botswana, Canada, and Australia.
Australia's diamond mines are major exporters of diamonds. For example, the Argyle Mine produces about eight million carats (1,600 kg) per year, and is the fourth largest diamond producing mine in the world, by volume. This is according to its Wikipedia page.
Diamonds come from mines, so issues related to mining apply to diamonds, too.
Coal mines are not known as a source of diamonds. Diamonds are erupted to earth through volcanic pipes.
'They' in this case, is Mother Nature. From WiseGeek: "Most chocolate diamonds come from diamond mines in Australia. The natural occurring brown color is thought to be created by the earth's pressure on the diamonds deep in the earth." Chocolate diamonds earn their colour by virtue of the stone's plastic deformation.
diamonds mines
Diamonds can be certified as non-conflict diamonds according to the Kimberly Process. In addition, some mines, such as those in Canada and Australia are not in conflict zones, which are found in Africa.
Most diamonds come from Africa, although businesses also mine for diamonds in Canada and Australia.
Diamond mines in Central & South Africa are where 50% of non-synthetic diamonds come from.