I find your deductions very convincing. What a great eye and memory you have.
After I saw the photos Nellie posted in 2013 I too saw a rose shape in the central element.
I wonder which of her rose of York brooches might have been used? The one given to her by the King or the one from the West Yorkshire regiment?
Below is a sketch of the rose of York brooch given as a wedding gift by the West Yorkshire regiment in 1893. Unfortunately, I don't have a photo (where I am certain of the provenance) of the brooch given to her by George V.
Queen Mary's use of various jewels in novel ways never ceases to intrigue me.
--Previous Message-- : I am quite sure this brooch is not the same as : the Countess of Wessex's wedding tiara (even : considering it could be mounted in a : different setting than today). : : My impression is that the "tiara" : worn in Melbourne in 1901 by Queen Mary : (then Duchess of Cornwall and of York) is : not a "real" tiara, but a head : ornament made from various elements : assembled together: : : - the two lateral "snail-like" : scrolling elements look strikingly similar : on this picture of Queen Mary in Melbourne : to the ones visible on this other picture of : Queen Mary - with a different central : element: : : : : : - the central element on the picture of : Queen Mary in Melbourne is probably one one : the diamond brooches in the shape of an : heraldic Yorkshire rose that Queen Mary : received as wedding gifts - see : http://members2.boardhost.com/royal-jewels/msg/archive/1413549745.html : Camilla, Duchess of Cornwall, occasionally : wore one of these brooches: : : : : : :