Ouch, sad development. Frank knows values, so I'm sure he'll post.
The way it would work here in the States is that the homeowners (or renters) insurance would cover specific damage to something while moving, although some policies require hard copy reference (written, photographic) of items that are at risk. Some folks just take pictures of every room in their house and add these to their policy portfolio. My policy has a basic $10,000 replacement limit for things specifically damaged in a move. There's also a separate clause for things specifically lost during a move.
If the Monart were mine this is what would happen, at least with my policy: After the fact, there would have to be an estimate of value by an expert in the field (antique dealer, author, lecturer, glass artisan), or a receipt of purchase. I'd also have to have the vase on a written or photographic list with the policy. The good news is that as we purchase items we can simply get a notorized note from a Notary Public as to new acquisitions and slip the note into the policy folder.
Insurance companies do make everything difficult, but if it's in print in the policy, you're golden. I guess if there's a silver lining, you prefer a different style and maker of glass over Monart, but I'm sure it's still difficult to deal with.