Another mystery is solved:

It looks like she wore a historic court train from the year 1878 see more
Princess Clarissa is wearing the Furstenberg Laurel Leaf Tiara on her wedding in July 2024.
It’s the same tiara which are used from her mother Freiin Diana of Berlichingen in the year 1992 when she married Maximilian Joachim Prince to Fuerstenberg.
We have a match to the new sketches from Stefan Sterns Grafische Sammlung H.Nalbandian Eaubonne
Maurice Duvalet, a great designer who worked for Cartier, Charlton & Co, Van Cleef & Arpels and the Rubel brothers, but whom all forgot to cite in their large books on the history of their house more about this talent follow the link of Jean Jacques information about him:
update from 2015
The Duchess of Gloucester wore the Cartier Indian Tiara when she attended the State Banquet in June 2024.
On her two row diamond rivieres she had pinned the wedding gift of the Duchess of Bedford, a large Baroque pearl brooch/pendant with diamond frame, to Queen Mary.
Three of her large daisy diamond brooches are put in front of her gown.
Queen Mary’s carved emerald from the Maharanis of India| England Royal Jewels
Queen Camilla’s earrings are not the Diamond Navette Flower Earrings from the late Queen Mother. We see small pavee setting in the closeup.
Elizabeth the Queen Mother’s Diamond Navette Flower Earrings are first seen in public on her in 1948, on the occasion of Pamela Mountbatten’s wedding.
The Diamond Earrings are one of the favorite jewels of Elizabeth, the Queen Mother.
Not sure but probably also from the Greville legacy.