Silver blue john marcasite shield ring r819 this femininesterling silver blue john and marcasite ringfeatures a circular central piece of blue john that has been sourced directly from treak cliff cavern castleton the striking stone issurrounded by sparklingpieces of marcasite set into a sterling silver shield and embellishinga classic silver band all our blue john jewellery is designed and crafted within our very own workshops in ashbourne derbyshire where a team of skilled craftsme