Agreed. It is the tiara Queen Alexandra received as part of her wedding gifts from Edward VII.
I think that it is easy to become confused when looking at the photo Franck posted because it is not as clear as some others.
Below are slightly sharper images from the Royal Collection where it is easier to see the upright elements belong to the wedding gift tiara.
Detail
I suspect that the photo below was taken on the same day, but I haven't checked.