Vintage Estate Signed 18 KTHGE and Black Aurora Borealis Resin Ring Size 4.75. This is a really sweet little vintage ring. It has a sitter of concave band that is signed with a makers mark and 18 KTHGE (18 karat heavy gold electroplated). The stone on this ring looks like a faceted hematite, but it feels like it's made of resin. It is a size 4 3/4.