You can see the famous Kohinoor diamond at the centre of Alexandra's new crown.
One of the largest cut diamonds in the world, Britain had acquired it when the Punjab was annexed in 1849. Prior to that it had had a turbulent history, with several owners.
It was shown at the Great Exhibition, where the general feeling was that it was rather underwhelming! So Albert decided to have it recut, so that it sparkled more. This reduced the weight of the diamond by almost half, but increased its brilliance.
Victoria used to wear it as a brooch, and there is a lovely Franz Winterhalter portrait from 1856, in the Royal Collection, of her in a scarlet off the shoulder gown wearing the vast Kohinoor brooch.
(Think of as not so much a brooch, more a bin lid!)
Later, Alexandra, Mary and the Queen Mother all used the Kohinoor as the centre piece of their crowns.
At present, India, Pakistan, Iran and Afghanistan all claim the Kohinoor diamond, so with the spate of ancient artefacts being returned to their original owners, maybe Charles will have it cut up and distributed to them, or perhaps Camilla already has plans for it!