Yes, this is a frequent Letizia move: the safety pin to secure the sash.
To be fair, here's a close up of the pin (or one of them, maybe she has one in silver/platinum as well?). It is indeed bejeweled:
And, because I must, the rest of this evening's look:
Moving on...I adore a full skirt, and I don't mind the little sleeved top either. But maybe an ensemble so simple is better suited to a sash with more interest than this one?
Oh, and also: it's been reported that Letizia has a new tiara (on which her fleur de lys brooch is supposed to be the centerpiece). Where is it? Hmm? Clearly she wasn't planning on using the brooch. Are you telling me she doesn't have the same need I do to play with my presents as soon as I receive them?