Every car boot sale regular dreams of the find of a lifetime. For one woman in west London, that dream came true, although it took her almost thirty years to realise it. The ring she picked up for a tenner turned out to hold a genuine diamond of just over 26 carats, and in June 2017 it sold at Sotheby’s in London for £656,750. Vanity Fair Italia has revisited the story of what is now known as the Tenner Diamond.
A box of bangles in Isleworth
In the late 1980s the woman, who has never been named, was browsing a car boot sale in Isleworth when a box of costume jewellery caught her eye. According to Sotheby’s, it was really the bangles she wanted. Tucked among them was a cocktail ring set with a single large, clear stone. The seller asked £12 for the lot; she haggled it down to £10 and took everything home.
She then wore the ring for decades as an everyday piece. Sotheby’s jewellery specialist Jessica Wyndham told the BBC that the owner wore it out shopping and day to day, with no idea it had any real value. That is easy to understand. The stone seemed far too big to be real, it sat in a worn, dark setting, and its old-fashioned cut did not flash like a modern brilliant.
From costume piece to auction star
In 2017 the owner finally showed the ring to a local jeweller, who suspected it was a real diamond but found it too large to weigh accurately. Sotheby’s sent it to the Gemological Institute of America, and the report was remarkable: a cushion-shaped diamond of about 26.3 carats, I colour and VVS2 clarity. Specialists believe it was cut in the 19th century, when cutters favoured a softer, more luminous glow over fierce sparkle.
Offered at the Fine Jewels sale on 7 June 2017 with an estimate of £250,000 to £350,000, the ring went for almost double the top figure. How such a stone ended up in a box of costume jewels at a car boot sale remains a mystery.
The charm of an old cut
The story is a lovely reminder that a beautiful ring is meant to be worn, not locked away. If you love the look of a big, clear centre stone, browse our rings, from aquamarine rings in icy blue to sapphire rings, or stack a few bangles as the original buyer intended. Our bracelets are made for everyday wear too.
Sources: Vanity Fair Italia, “Comprato per 10 sterline a una bancarella pensando fosse bigiotteria” by Filippo Iarocci (29 October 2026); Sotheby’s, “The ‘Tenner’ Diamond” and Fine Jewels lot 364 (June 2017); BBC News, “Car boot sale diamond fetches £650k at auction” (7 June 2017); The Guardian / Press Association (7 June 2017). Featured image: AI-generated scene.
