Blue John

Discovered nearly two thousand years ago by the Romans, Blue John is a rare natural variety of calcium fluorite, highly distinctive and prized because of its characteristic bands of coloured veins.

History of the Blue John stone

The only known deposit of this unusual mineral occurs in a hill to the west of Castleton in Derbyshire, England, opposite the mountain known as Mam Tor “The shivering mountain”.

The Romans settled just three miles from the area at Brough. It is likely that they were searching for deposits of lead ore and struck upon an outcrop of Blue John by chance. Being keen mineralogists, they would instantly have recognised the outstanding beauty of their find.

At this time, the technology must certainly have existed to enable the complicated process of turning and polishing the stone. The principal colours are purple and white, disposed in undulating bands and usually separated by a third band, the two colours being mixed, assumed to the tint of the flame.

The Blue John Caverns

Blue John is a very crystallised formation and occasionally surface marks can be seen. This is not detrimental to the stone and in fact enhances its individuality. The origin of its blue colour remains uncertain.

The creation of Blue John began when the Treak Cliff and Blue John caverns were formed as mineral solution settled in the cracks of limestone, driven up from the depths of the sea by volcanic forces around 250 million years ago.

Small veins and nodules of fine quality stone of sufficient size for jewellery can still be found. But in modern times the caverns are mainly for show; open to the public for guided tours and a popular destination for visitors to Castleton.

Blue John and Castleton

There are records alluding to the mining of Blue John as far back as the 18th century. The stone was originally used to create decorative vases, fireplace panels and various other ornamental items. By the 19th century, output had increased in the mines surrounding Castleton and the handcrafting of Blue John jewellery began.

Splendid specimens of Blue John stone can be found in important collections throughout the world. But despite its international appeal, the deposits in the hills surrounding Castleton are still the only known sources of the stone in the world.

Any raw extracts that are found are kept within Castleton for exclusive use by the local workshops.

ASD Jewellers

ASD Jewellers is one of the longest running Blue John workshops in Castleton. For over 40 years, we have built a unique collection of quality Blue John jewellery, set in 18 or 9 carat gold or sterling silver, for the discerning collector to cherish.

Items from ASD’s Blue John collection can also be found in fine jewellery stores in Sheffield, Chesterfield and London’s Covent Garden.

Read more about the history of ASD Jewellers.

The home of Blue John Jewellery

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