Is this a new creation by Chaumet, or an older piece? It actually looks like an assortment of antique brooches assembled as a tiara, rather than as a "real" tiara.
The central flower, with its carved emerald, reminds me of a corsage brooch (by Faberge, if I well remember?) which belonged to a Russian Grand-Duchess, and which was pictured in various books about the Russian imperial jewels.
Beautiful, anyway, and certainly worth to adorn the head of a Queen!