Dear Dave,

The Emerald Tiara given to the Grand Duchess Xenia by her Father seems to be in the nature of a Coronet, if we are talking about the same item ?

I can see why Queen Mary never wore it [in public] since her own Delhi Durbar tiara is not dis-similar, is rather more beautiful, and because had close personal associations to Mary, both as Queen-Empress of India, and because its use of her [family] Cambridge Emeralds.

Presumably the descendant [resident in England] is Princess Olga Romanoff, who may well 'be in a position' to know details of the fate of her Grandmothers Jewels, and which of them are now in the possession of her third Cousin, HM King Charles 111

Best regards

Jonathan