Sri Lankan seeks $300m for rare blue star sapphire

A Sri Lankan gem trader who owns the world's largest blue star sapphire has decided to sell the dazzling stone, with a dizzying asking price of $300 million.

The rare, egg-shaped stone weighs 1,404.49 carats and has been authenticated as the biggest of its kind at the Gemological Institute of Colombo (GIC), a private laboratory in the Sri Lankan capital.

"Looking at the reserve price of other very famous gems, I have now valued this at over $300 million," the owner, who wants to remain anonymous for fear the stone might be stolen, told AFP.

Unlike blue sapphires which have complete clarity of colour, blue star sapphires, a form of corundum, are opaque -- but when placed under light reveal a six-line star.  

Industry experts said the stone was so rare it was impossible to give a valuation.

"We can't put a price on something like this. It is so rare and unlike other (smaller) sapphires, this is not a stone that can be replaced," Ashan Amarasinghe, leading gemologist with the GIC, told AFP.

"This is something only collectors or museums can afford," he said.

The owner said he based his asking price on the Black Star of Queensland, a star sapphire which was reportedly sold for $100 million in 2002, although details were not publicly disclosed.

The gem, named Lankan Star of Adam by its owner, beat the previous record for the biggest stone of its kind -- also held by a Sri Lankan businessman -- by about nine carats.

Both sapphires were found in Sri Lanka's central region of Ratnapura which is known as the island's gem capital, industry officials said.

The owner said he bought it for an undisclosed price in September before realising the rarity of his find -- which he has kept a closely guarded secret.

"I have lived in affluence, but now I feel even more blessed," he said. "This (find) has not changed my lifestyle. But, I feel thrilled to be the man owning this gem. It is good for the ego."

Sri Lanka is known for its blue sapphires, one of which was used in the engagement ring of Catherine Middleton, the Duchess of Cambridge, and formerly owned by Princess Diana.