I would like to solve just what these earrings are. They could be the two diamonds Queen Mary removed from the QV/coronation necklace to make earrings. Found nothing about them in the QD. They might be the earrings Field names as Queen Victoria’s Stud Earrings but actually Queen Mary’s as explained above. It seems that Queen Mary never wore the QV/coronation earrings but only ever used the bottom two-thirds as drops on brooches.
The QV/coronation necklace and earrings are shown here to compare sizes. Queen Mary's earrings are far too large to be the top third of the QV/coronation earrings.