LONDON.- One of the world’s rarest stones, a blue diamond, has sold for £1,889,250 at the Bonhams Fine Jewellery Sale in New Bond Street. Originally estimated to sell for £600,000 – 800,000, the stunning diamond and blue diamond crossover ring made by Bulgari circa 1960 received an unprecedented amount of interest from national and international clients. The ring came from a private European collector and had never been seen at auction, resulting in a prolonged bidding session, with multiple bidders battling for the top lot. The ring finally sold to a bidder on the phone. Typical of Bulgari’s elegant simplicity, the ring offered by Bonhams was set obliquely with a pear-shaped diamond, weighing 3.93 carats, D colour, VS2 clarity, and a pear-shaped fancy vivid, natural blue diamond (the highest grading for a coloured diamond), weighing 3.72 and SI2 clarity. This meant the blue diamond sold for £492,000 per carat. The