According to George Hamel, a gemnologist who worked for Court Jeweller Steltman in The Hague, the provenance of the Dutch Sapphire Tiara is: Maison van der Stichel in Amsterdam.
He presented his case during the Silverstad Symposium in Silver city Schoonhoven. He has found a newspaper article from 1898 stating that the Tiara was made at that firm. He also claims the central sapphire was not an heirloom (brooch) from Queen Anna Pavolvna.