I visit 1stdibs fairly regularly and while I too wonder who would acquire a piece worth several 100 000 USD online (and there are quite a few in this price range), occasionally interesting historical pieces are advertised by well-known traders and galleries and some of the HQ-fotos (reverse sides, mountings, technical aspects) are very enjoyable.

The tiara in question is offered by Wagner Preziosen, a trader in Berlin, who has published a short article on that piece which apparently was commissioned by a "Swabian-aristocratic family".

How the centre elements are connected with flexible metal bars to allow for more distance when used as a choker is quite interesting, as is the intact presentation box with its divisions for various fittings.