THE largest pair of diamonds ever mined in Australia are now on sale.

At seven carats each, the "perfectly matched" gems are being sold by Sydney jewellers J. Farren-Price for $550,000.

It is a rare opportunity for an Australian to own a piece of natural history, chief executive Julian Farren-Price said.

The previous largest pair to come out of Argyle mines in West Australia's Kimberley region were a comparatively measly two carats each. Only five single diamonds weighing more than eight carats have been mined at the site.

"It would be a great pity if an Australian does not buy these national treasures," Mr Farren-Price said.

The pair of princess-cut white diamonds will be available until September 12. If not sold, they go to a jewellery fair in Hong Kong.

Mr Farren-Price said he had already had "serious" interest from three private clients.

"Some people would buy these as an investment, some people will buy them for the fact that they have a unique historical setting, and some people will buy them because they are fabulous diamonds," he said. "They are certainly a collector's item."

Mr Farren-Price said that a strengthening economy in China and India meant more people were entering the luxury market, driving up demand and prices.