I think you are right ! I also do think the emerald and diamond tiara was in the legacy.
We have to bear in my mind that Queen Elizabeth the queen mother might have worn this tiara for an private event or exemple...and that can be the reason why we have no photo of her wearing this tiara.
--Previous Message-- : In this message posted in November 2015 : http://members2.boardhost.com/royal-jewels/msg/1448090703.html : Beth had given a link to an archive of the : Australian Women's Weekly of March 1st, : 1947, which mentions the Greville bequest : (fourth column). Among the Greville jewels : mentioned in this article is " a tiara : of diamonds and cabochon emeralds with a : ring and pendant earrings ": : : http://trove.nla.gov.au/ndp/del/article/47506020?searchTerm=%22Mrs%20Ronald%20Greville%22&searchLimits=exactPhrase=Mrs+Ronald+Greville : : So this is another source, besides Vincent : Meylan's book (which I consider very : reliable, as Vincent Meylan had access to : Boucheron's archives), which suggests that : this emerald tiara was part of the Greville : bequest. : : :