.20 Art Deco Diamond Engagement Ring in 18K White Gold. This Art Deco engagement ring features a .20 carat Old European cut diamond mounted in an elegant filigree design of 18 karat white gold. The center stone glitters against the white gold and is set in prongs inside a geometric mounting. Surrounding the diamond, fabulous filigree metal work with milgrain details decorate the head of the ring. Swirling across the gallery and melting into vintage engraved shoulders, this engagement ring is a work of art.