The ring in question is thought to be from Collins and Sons, boasting a 20-carat aquamarine. Set in platinum, the experts reveal the style appears to be a cushion-cut stone. Duchess Sophie ...

and a Jean Schlumberger by Tiffany ring; Ariana Grande in a pendant and earrings in platinum with morganites and diamonds, and Gabrielle Union in a necklace in platinum with aquamarine ...