A hoard of gems accrued over 40 years by a collector who “loves sparkly things” is being sold in Britain with a retail value of £8 million ($12.4 million, 11.1 million euros), an auction house said Friday.

Rubies, emeralds, tanzanites and sapphires “ethically sourced” from all over the world are among more than 680 gemstones being sold from the largest collection of its kind in Britain, John Pye Auctions said. Their anonymous owner hopes to take advantage of a rising value for gems.

“Auction rooms across the globe are seeing record-breaking sales,” said Sheldon Miller, a director of the auction house, which will sell the first lot in September. “We are expecting substantial interest from international buyers. It is extremely rare a collection of this purity and size comes to the market.”

Although they were originally sourced as loose gems, in many cases directly from the mine, the stones on sale have been set and mounted against diamonds as pieces of jewellery. Among them is a matching set of 35-carat Zambian emerald earrings with an estimated value of £500,000 to £600,000.

The owner started the collection after buying a rare 133-carat tanzanite four decades ago, travelling all over the world, including to Myanmar, Sri Lanka, Tanzania and Zambia. “I love sparkly things,” the collector said in a statement.

“I love the buying, the finding of the mine and acquiring the very best stones. The best mines from all over the world come directly to me with their finest stones.”