Grey Agate (Gold Foil) is a semi-precious gemstone surface — a Mosaic of polished grey​/​brown​/​amber agate cross-sections set in bright gold foil, with translucent banded nodules — a dramatic backlit semi-precious gemstone surface. slab with a polished finish, often backlit as a feature panel, vanity or bar front. A dramatic decorative stone for interior feature applications.