I guess one of the main problems in creating a modern tiara is the abandonment of ornament in modern design. And from our point of view a tiara is the ultimate ornament... But apart from joking a lot of modern jewellery is very clear and restrained, low-key and concentrated on clear forms, notably circles. Which disturbs me for example at the Ocean Tiara of Princess Charlene of Monaco – the circles are too accentuated, too much constructed, not organic. For my taste. The outline of the Ansorena Tiara of Queen Letizia is reduced to the minimum. To say so its a idea of ornament. Consequently the are no fittings for the pearls. I suppose a design especially not using big stones like this is also helpful limiting the costs. It is possible that the pearls on top are choosen to 'upgrading' the basic Ansorena design, made for the collection, for the Princesse of Asturia? In the end it is much better than the “DeBeer meets Disney”-pieces out there.
An other way to create a modern tiara is the alternative path of choosing a floral design. It allows much more decoration than “modern reduction”. The Midnight Diadem is extraordinary, an interpretation of an old theme in timeless artwork. Good danish design!
PS: On the other hand P Charlene´s modern aigrette is a good example for a modern wearable headpiece. It could help to made a renaissance of wearing jewels on the head even if real tiaras are not appropriate.