Vintage Square Prong Diamond Engagement Ring in Platinum. This classic Art Deco square prong diamond engagement ring is incredibly detailed and features a spectacular Old European cut diamond at the center. The fine detail down the entire shank is truly special, with flowing engravings down all three outside edges. The shoulders are adorned with six .015 carat accent diamonds that are bead set, with extremely fine milgrain detail outside of them. This is a beautiful example of skilled craftsmanship from the Art Deco era!