I once read that it was because the Braganza tiara was the heaviest of all the tiaras, and to the Nobel ceremony the Queen would have to wear it for many hours (the ceremony and then the banquet...). It would cause her great disconfort and perhaps migranes to wear it for a long period of time...
--Previous Message-- : Lovely Queen Silvia! I find strange that of : all the times she wore the Leuchtemberg : sapphires and diamonds suite or the nine : prongs diamonds tiara (fewer times the : Connaught diamonds tiara or the cameos : parure), she did not wear once the imposing : Bragança diamonds tiara that she wore on : Princess Victoria's wedding day. :