Below a picture of Queen Wilhelmina in the Concertgebouw, most likely wearing that diadem. Click on the picture to zoom.
Technically not unwearable (the Fürstin von Thurn und Taxis with her sapphire diadem proves it) but esthetically it is unwearable for the changed taste since 113 years ago. The fact that exactly this diadem has been broken up is a proof that little tears were shed by the Oranges for the loss of this.