So it’s not strictly speaking a jewel, though here is a photo to remind you of the genius that is Joel Arthur Rosenthal, known simply as JAR.
It is a link to a fabulous interview with the famously reclusive Rosenthal, running in the new issue of The Economist Magazine Intelligent Life.
And the jewellery pictured here? The magazine notes it is an, “Orange peel and orange blossom brooch, in garnets, diamonds and enamel, silver and gold, from 2001. The garnets are mounted in blackened silver, a material Rosenthal uses so as not to distract from the stones.”

The orange peel and orange blossom brooch in garnets, diamonds and enamel; silver and gold by JAR.