Sapphire and diamond ring, circa 1950. The 4.3 carat sapphire at the centre of this ring is faceted has an unusual mixed cut, which shows off its splendid shade of blue. Lovers of sapphires will immediately recognise this as the perfect example of the classic ‘Cornflower’ blue – a dreamy mid-blue with a hint of violet, most strongly associated with Sri Lankan stones. Sri Lanka is the most historic source of sapphires, but the vast majority of its stones are heat treated to improve their colour. This stone is remarkable not only for its beautiful colour, but for its total lack of treatment – a rare combination. Set within a border of brilliant-cut diamonds, this sapphire and diamond ring is a beautiful and extremely high quality example of a classic cluster ring – an enduringly popular design for engagement rings, as favoured by Princess Diana, and more recently, Kate Middleton, Duchess of Cambridge.