Gem giant steals the show and the crown

This is one precious gem that is not for sale.

Owned by Cygnet Bay Pearls, Australia's oldest cultured pearl farm, it is perhaps the world's biggest fine-quality round pearl.

It is back home in Broome after touring the globe to substantiate the claim.

Round, white pearls are the most valuable pearls - and bigger sizes the hardest to grow.

Unblemished, with a sought-after white-pink hue, it is twice the size of an average South Sea pearl - measuring 22mm and weighing 156g.

In possibly the most effective method to ensure it was the world's biggest pearl, Cygnet Bay's distributor, Autore Pearls, exhibited the pearl at trade fairs and found no dispute to the claim.

Cygnet's general manager, James Brown, said this was an achievement all of Australia could be proud of.

The pearl was harvested at Cygnet Bay pearl farm, on Dampier Peninsula, north of Broome, as part of a bumper crop in 2004 and the company says it has turned down multimillion-dollar offers for the gem.