That's an interesting question. The princess wore it in 2005 at the prewedding ball of duchess Elisabeth in Bayern & Daniel Terberger. Maybe the tiara is still owned by the family and they loaned it to the museum. Or it's the other way round. I didn't find anything about it on the site of the Münchner Residenz.
--Previous Message-- : Why did she wear the diadem? I think that it's : the property of the Governement (it's : exposed in the Residenz of Munich). : : Regards! :