Thank you, Baxter, for the correction. I had made a confusion with another pair of wing brooches made by Chaumet (which can also be mounted on a tiara frame) which includes blue translucent enamel (which I had erroneously taken for sapphires). But after verification, this blue enamel version was made for Gertrude Vanderbilt Whitney in 1910 (source: https://x.com/Chaumet/status/1255904736685035522) and seems to be now part of Chaumet's historical collection.



Obviously, the double wings brooch/tiara was a popular jewellery model in the first half of the 20th century, and Chaumet produced several versions of this jewel, with various stones, or with only diamonds.