A blue John patinated and gilt-bronze vase, England, early 19th century

For a similar vase in blue john, see Sotheby's Paris, "Hôtel Lambert, une collection princière, volume III", October 13, 2022, lot 685.

Discovered almost two thousand years ago by the Romans, blue John is a rare natural variety of calcium fluorite, with distinctive colored veins. The only known deposit of this unusual mineral was in the hills west of Castleton, in Derbyshire's Esperance Valley. First mentioned in the late 17th century, blue John became increasingly popular in the second half of the 18th century, being transformed into decorative and architectural objects, notably fireplaces. One of the pioneers of this type of work was Robert Adam, although the material is perhaps most famous today through the works of Matthew Boulton, Birmingham silversmith and gilt bronze manufacturer. Much of the stone's extraction has gone into the manufacture of gilded bronze objects, in the form of elegant candelabras, urns, vases and incense burners. These objects are all the more sought-after as the blue John mines are now largely closed.