But long before their reign, a far less dazzling gem captured the hearts of jewelry lovers — and now it’s making a comeback. Jet, a flat-black, opaque gemstone derived from wood that has ...

‘I discovered it in my final year at Central Saint Martins,’ notes Ms Cullen. ‘I had a box of samples from a gem dealer and when I picked up the jet, I had a eureka moment. It is an amazing material.