Containing a portrait of the King, painted on sections cut from a diamond by the royal painter Richard Cosway, the object set an artist record for a portrait miniature.
The gold jewel, set with diamonds, is one half of a pair. The other contained an image of the king’s secret and illegal wife, Maria Fitzherbert.
This surviving half, known as The Maria Fitzherbert Jewel, passed down through descent directly from Fitzherbert. The family recently decided to sell the jewel and it was offered with an estimate of £80,000-120,000.
George IV, the then Prince of Wales, is thought to have met Fitzherbert at the opera around 1780.
Their marriage, in secret, in Mayfair in 1785 was illegal because Fitzherbert was a Roman Catholic.
Nine years after this secret nuptial, George IV was bribed to wed his cousin, Caroline of Brunswick, with the government promising to pay off his enormous debts. Although this marriage was brief and he reunited with Fitzherbert soon after, his wandering eye led them to separate in 1811.
However, experts suggest his love for Fitzherbert remained: he wore the locket containing her picture on his deathbed, before it was buried with him at Windsor Castle.
The Maria Fitzherbert Jewel, sold as part of Christie’s Exceptional sale on July 6, was the second highest result of the auction.
Two carved marble lions (circa 1335–1402) from the funerary monument of Charles V of France were the top lot, hammered down at £8.2m.
The 25-lot auction made a hammer total of £10m and 72% of the lots sold.