Nico, here is a citation to a NY case where Christies was enjoined from transferring an item whose title was in dispute. http://www.courts.state.ny.us/Reporter/3dseries/2011/2011_50887.htm Of course, it's possible that HK or Swiss law may apply,but there is an argument that NY law could apply, and if so, Antiquorum should have followed this case law precedent and retained the watch until title is resolved. It may be too late as a practical matter since they released the item to the consignor, but I would bring this to Antiquorum's attention and let them know that they could be liable for not observing their legal responsibility as set forth in this case. Perhaps faced with such a threat they will at least disclose the identity of the consignor to you.
Best,
Descartes