Product Description:This simple pendant is set with a large and stunning example of Blue John that measures 40x30mm. Blue John is a very rare gemstone as it is only found in Castleton, Derbyshire. This cabochon is made up of a large slice of Blue John that is protected by a cover of clear crystal. This is a great collector's piece as the supply of Blue John is disappearing fast! It is quite unusual to find a cabochon of this size.