Perth Mint unveils Australia's most expensive gold-diamond coin

Australia's Perth Mint has unveiled this week the most expensive collector coin in the country' history - a diamond-encrusted treasure valued at $2.5 million ($1.8m).

Made of 99.99 percent pure gold, the coin features four rare Argyle pink and purplish-pink diamonds. The largest is 1.02 carat.

Named the Discovery Gold Coin, its design was inspired by the holey dollar, which was introduced by governor Lachlan Macquarie in 1814.

From a gemstone perspective, each of the four fancy pink diamonds in the coin's reverse is accompanied by an original gem identification and authenticity document from Argyle Pink Diamonds. (Image courtesy of Bill Johnston | Twitter.)

The 2kg-coin comes in two parts, an outer ring and a centrepiece emulating colonial Australia's first official coinage - the historic "holey dollar and dump."

The coin will be on display at The Perth Mint's retail store until the end of September, unless a collector with quite a bit of cash to spare snatches it earlier.