Retro Two-Tone Diamond Engagement Ring in 14k.  This beautiful Retro engagement ring features a .39 carat Old European cut diamond set in 14 karat white and yellow gold. The center stone is set with fishtail prongs, which creates somewhat of a square mounting, and is further accented by single cut diamonds on the shoulder. The shank is yellow gold and creates a nice contrast with the white gold on the face of the ring.