A few hundred exceedingly rich and discerning collectors are the target market for a new diamond-encrusted, one kilogram gold coin struck by the Perth Mint.

The 99.99 per cent pure gold coin, known as the Kimberley Treasure, has been inset with a purplish red Argyle diamond worth about $950,000.

The coin depicts a red kangaroo holding a 0.54 carat red gemstone between its front paws, with Queen Elizabeth II pictured on the other side.

"The Kimberley Treasure is the only coin in the world to feature a radiant red diamond from the Argyle Diamond Mine," Perth Mint CEO Richard Hayes told people gathered at the Mint for the coin's release.

Apart from its status as a one-off collector's item, the coin is also legal tender in Australia.

WA Premier Colin Barnett was at the Perth Mint to unveil the coin, which goes on the market today.

"I don't know who will buy it. Someone will buy it. It will make a lovely gift for the lazy million dollars," Mr Barnett said.

Mr Hayes said he expected strong interest in the unique item.

"We think we'll have significant interest, we think mostly from overseas, but there will be significant interest in it," he said.

"I would estimate there's probably a couple of hundred people [worldwide] who would be interested in something like this.

"It would appeal to a very, very high net worth individual who is a collector of things unique and of things rare."

Prospective buyers will be able to view the coin until late August.