Retro 1.22 European Diamond Engagement Ring in 18k Platinum.  This gorgeous Retro engagement ring features a stunning 1.22 carat Old European cut diamond set in platinum with an 18 karat yellow gold. The stone is secured with four (4) flat prongs and below it sits rows of small accent diamonds. The basket reaches up beautifully which can be seen from the side profile, and the look is completed by the warm yellow gold shank that is polished to a smooth sheen.