.36 Mid-Century Halo Diamond Engagement Ring in Platinum. 36 Mid Century Halo Diamond Engagement Ring in Platinum. This lovely vintage engagement ring features a . 36 carat round diamond in an amazing platinum setting. The primary stone is held in a floating bezel adorned with milgrain detail. Outside lies a beautiful halo of round brilliant cut diamonds weighing . 48 carats. The basket has intricate filigree wires which create plenty of windows for light to enter the diamonds. This is a gorgeous example