When Princess Mary was the Duchess of Cornwall and York, she was photographed wearing an emerald shamrock brooch (note the Cambridge emeralds in an earlier version as necklace).

In 1902 the press noted:
The Princess of Wales, in a plainly-made gown of grey with heliotrope chiffon in her straw toque, wore some lovely jewels and the pretty compliment of donning her magnificent shamrock brooch, formed of big emeralds set with diamonds, was much appreciated. She visit 20, Arlington Street to make a tour of the stalls of the Irish Industries Association.

What's the story of that trefoil brooch set with emeralds and diamonds?

Is it one of the mysterious wedding gifts to Princess Mary of Teck? It could be not the Galloway brooch, because it was noted as a clover brooch of four petals.

Is it the emerald and diamond brooch, which was given to the then Duchess of Cornwall and York, by the Grand Duke Nicholas Tsarvich of Russia?

What we do know is that Duchess Marina of Kent wore it on the important occasion of the engagement of her eldest son, the Duke of Kent.

She probably left this jewel to her second son, Prince Michael of Kent, as his wife Princess Marie-Christine, on the right side above, wore the shamrock brooch on different royal occasions.