9ct yellow gold blue john stone windmill necklace p2534 this petite femininewindmillshaped pendant has been created using the highest quality blue john which has been expertly hand carved in our local workshop the blue john is sourced directly from the treak cliff cavern in castleton derbyshire the gemstone is set within a 9ct yellow gold swirl design frame and is sold complete with an 18 inch yellow gold all our blue johnjewellery is designed and crafted within our very own workshops