EXCLUSIVE AT NET-A-PORTER. JIA JIA's founder is inspired by the natural beauty of crystals, so she highlights their unique features in all of her designs. This necklace is handmade from 14-karat gold and centered by a striking crystal quartz that's uncut, untreated and mounted in a diamond-encrusted setting. The chain is adjustable, so you can customize the length. -- Crystal quartz, total weight: 20.00-carats; round brilliant-cut H I1 diamonds, total weight: 0.13-carats - Lobster clasp…