Blue diamonds are extraordinarily rare and over the past ten years fewer than thirty of them over five carats have appeared at auction worldwide. The famous historic blue diamonds – the Hope, the Wittelsbach-Graff and the Tereschenko - are believed to have come from the legendary Golconda mines in India and share a high degree of transparency and liquid fire. This diamond certainly possessed these properties and its flat, antique cut also suggested an alluvial Golconda diamond. It was mounted in a 'Trombino' ring made by Bulgari in the mid 1960s. During the 1950s, Bulgari has bought up many natural coloured ancestral diamonds from maharajas and nawabs as well as purchasing a fabulous collection of fancy-coloured diamonds amassed by a French dealer. The company soon began to incorporate these coloured diamonds into contemporary jewels of the finest quality of which the 'Trombino' is a outstanding example.