Authorities in Sri Lanka say that the world’s largest star sapphire cluster has been accidentally discovered in a backyard.

A gem trader explained that the stone was found by workmen who were digging a well in his home, located in the gem-rich Ratnapura area.

Experts say that the stone has an estimated value of up to $100 million (£72 million) in the international market.

The cluster weighs around 510 kilograms or 2.5 million carats, is pale blue in colour and has been called the “Serendipity Sapphire.”

“The person who was digging the well alerted us about some rare stones. Later we stumbled upon this huge specimen,” said Mr Gamage, the owner of the stone, reported the BBC.

Mr Gamage, is a third-generation gem trader and on discovering the sapphire informed authorities about the find. However, it took over one year to clean the stone of mud and other impurities before it could be analysed and certified as a sapphire.

Some stones fell out of the cluster during the cleaning process, these were found to be high quality star sapphires, said Mr Gamage.

Experts have however pointed out that even though the specimen has a high carat value, this may not apply to all the stones in the cluster.

The name Ratnapura means city of gems in Sinhalese; the city is known as the gem capital of the South Asian country.

Sri Lanka is a leading exporter of precious gems including sapphires, indeed in 2020, the country earned about half a billion dollars through the export of gems, cut diamonds and jewellery.

The news comes as Sri Lanka’s gem industry has suffered losses as a result of pandemic induced lockdowns.

Many who work in the industry hope the the “Serendipity Stone” will act to attract international buyers and experts.

“It is a special star sapphire specimen, probably the biggest in the world. Given the size and its value, we think it will interest private collectors or museums,” the Chairman of the National Gem and Jewellery Authority of Sri Lanka, Thilak Weerasinghe, said.