A rare four-carat blue diamond is set to go under the hammer with an estimated price tag of £1.5m at Bonhams London Fine Jewellery today. 

The sale of 188 lots includes a selection of white and coloured diamonds, sapphires from Kashmir, Burma and Sri Lanka, signed jewellery from Cartier and Van Cleef & Arpels, and the largest private collection of jewellery ever to come to auction by Anglo-Italian designer Andrew Grima.

Headlining the sale is a ‘Fancy Intense Blue’ diamond estimated to be worth between £1.2m-1.5m The pear-shape diamond, weighing 4.03 carats, has been in a UK private collection for over 30 years and is now set to go to a new home.


According to the Gemmological Institute of America, only one in 10,000 diamonds has a fancy colour, which makes such stones rare and highly sought after.

Coloured diamonds have, on average, increased in value by 100% over the past decade with blue stones showing the strongest growth over the past 12 months.