When the circumstances are optimal, old rose cut diamonds can unfold a magical splendour. Brilliant cut diamonds however can glitter in less optimal circumstances too because these simply have more facettings and possibilities to break, refract and reflect the light.
I am not sure if the diamonds in the Boucheron Honeycomb Motif Diadem (the Mrs Greville Tiara) are rose cut, but every time I see this diadem, I am struck by the splendour. It is surprisingly modern as well, given the age of the design. It suits HRH The Duchess of Cornwall very well.