London Blue Topaz and Diamond Halo Ring Blue Topaz 3.8 ct. Diamond 0.43 ct. 18K White Gold Other Products. Diamond ring Diamond 0.07 ct. 18K White Gold More Detail Diamond Halo Earrings 18K White Gold More Detail Golden South Sea Pearls and Diamond Halo Earrings Golden South Sea Pearls and Diamond Halo Earrings in 18K Yellow Gold More Detail Plain Ring 18K White Gold More Detail