.80 Art Deco Two-Tone Diamond Engagement Ring in 14k. 80 Art Deco Two Tone Diamond Engagement Ring in 14k. This Art Deco engagement ring features a . 80 carat old European cut diamond set in six prongs. The embellishments around the Old European Cut center diamond have tiny ornamental designs, curling down the shoulders of the band. Created in the Art Deco era between 1915 1939, this antique engagement ring has an enduring, timeless style. Truly breathtaking!