Thanks for sharing Beth, the tsarina's ownership gives this very famous tiara an enhanced provenance. It’s interesting to remember that Grand Duchess Vladimir also received from Empress Maria Alexandrovna an impressive riviere necklace of large diamonds which was also purchased by Queen Mary at the same time as the tiara. Those diamonds would later be included in her diamond sautoir created in 1928, and with the tiara would be inherited by Queen Elizabeth II.
See link to Frank’s earlier post https://mb.boardhost.com/historyroyaljewels/msg/1641737637.html