Estimated at £1,200,000 - 1,500,000 ($1.5 - 1.9 million), a Fancy Intense Blue diamond will headline Bonhams London Fine Jewelry sale on September 20. The auction house states that the pear-shape diamond, weighing 4.03 carats, has been in a UK private collection for over 30 years. According to the GIA, only one in 10,000 diamonds has a fancy color, which makes such stones rare and highly sought after. Often referred as "miracles of nature", colored diamonds have, on average, increased in value by 100 percent over the past decade with blue stones showing the strongest growth over the past year (+5.5%), according to data from the Fancy Color Research Foundation.
Jean Ghika, Head of Jewelry for Bonhams UK & Europe, said: "We are delighted to bring this exceptional stone to the market. Blue diamonds are extremely rare and highly coveted. We are looking forward to showcasing this stone, along with other selected lots in London, New York, Hong Kong and Geneva, where we anticipate considerable interest." The second headline lot is a Fancy Colored Diamond brooch featuring a central square step-cut Fancy Gray-Blue diamond, weighing 4.83 carats, with a Fancy Dark Brown-Greenish Yellow step-cut diamond to either side, weighing 2.51 carats and 2.38 carats respectively, suspending a pear-shape Fancy Pink Diamond drop below, weighing 1.90 carats. The brooch dates from the mid-20th century and has a pre-sale estimate of £650,000-850,000 ($833,000-$1.1 million).
The sale of 188 lots includes a selection of white and colored diamonds, sapphires from Kashmir, Burma and Sri Lanka, signed jewelry from Cartier and Van Cleef & Arpels, and the largest private collection of jewelry ever to come to auction by Anglo-Italian designer Andrew Grima.