Vintage Old European Diamond Art Deco Engagement RingVintage Old European Diamond Art Deco Engagement Ring. This original antique 18 karat white gold Art Deco ring is set with a . 66 carat old European cut center diamond. The center diamond is bead set with a decorative square bezel creating a geometric appearance popular during the 1930s. There is an design element at the North and South points of the center diamond that is finished with a milgrain edge. The center diamond is accented by a row of