Though it's not a new brooch, this one's provenance is still something of a mystery. It appears to be a small bouquet of different colored stones (sapphires and more, perhaps?) with stems tied together. And it's a tricky little trinket too, because the multiple colors give it a different appearance from every angle.
One possible provenance could be this brooch described by Leslie Field in The Queen's Jewels but not definitively tied to any single brooch since: "a Cartier floral spray set with sapphires, rubies, diamonds and an aquamarine, which her parents gave her in 1943." There is at least one other brooch which may be a better match for that description, however. Lacking any confirmation, I will dub it the Multi-Color Floral Spray Brooch for the time being.