Have a chance to purchase an early A. Lange & Sohne PW. Serial #20373 with gilt movement. My question............ were ALL of these PW's cased in A. Lange & Sohne marked cases. It is a 3rd generation watch to the same original family. Dial seems correct. Movement correct. However, the gold case has a personal inscription and matching serial numbers on it. No indication of gold content, ie .585 or .750.

Any help or guidance would be appreciated!