In the pink - yours for $2.3m

A model displays a $2.3 million tiara. The centre of the tiara detaches to make a ring. Photo / Natalie Slade

Stuck for gift ideas for the woman who has everything? This tiara of 178 rare pink diamonds set in platinum and rose gold will set you back $2.3 million.

But for this price, you do get two pieces of jewellery. The centre of the tiara detaches, and with a little fiddling, can be fastened to a band to form a ring.

The tiara has been brought to New Zealand by Partridge Jewellers, the New Zealand partner to Rio Tinto's pink diamond business.

It was designed and made by royal jewellers Asprey of London, and took almost a year to construct, although most of the time was taken in finding and matching the stones. These range in colour from "fancy intense pink" to "fancy vivid pink".

Pink diamonds are among the most valuable in the world because of their colour and rarity. They are only 0.1 per cent of all diamonds mined or found worldwide.

These ones come from Rio Tinto's Argyle mine in the northern region of Western Australia, which produces about 90 per cent of the world's pink diamonds.

The origin of the pink colour is unknown, although it is thought it occurs as a result in a change in molecular structure of white diamonds after their formation in the earth's mantle.

Aboriginal people in the region have a much more captivating explanation for the colour.

They says three local woman trying to catch a barramundi were foiled when the fish escaped.

It jumped through their net to land where the mine is now, and the colours of its diamonds came from different parts of the fish, pink coming from its heart.

The tiara returns to London via Hong Kong, Shanghai, Beijing and New York.

There is also a necklace, designed and made in the same Asprey workshop.

It has a five carat white diamond, with blue, pink and yellow stones, and is available for $880,000.