I think we can agree on our disagreement on this point.
I think the tiara, though a large one, is not overwhelming (or at least not as much as the Thurn-und-Taxis sapphire tiara). If you compare on the picture, it does not look bigger than the tiaras worn by Princess Olga of Yougoslavia or Princess Kira of Prussia:
But I agree that such large tiaras require an appropriate hairdo to be worn both elegantly and comfortably.