For decades, Gogo Ferguson has been designing bold, sculptural jewelry inspired by the beauty of the Cumberland Island coast, and her pieces have picked up a devoted, insider-y, “if you know, you know”-type following along the way. The line is both sophisticated and wild, exquisitely crafted yet not too fussy, and made exclusively in Cumberland Island, Georgia, where Gogo's family has lived for generations. This ring is cast in gold from an armadillo scapula, an especially beautiful part of…