You'll find that the R Malerne brand clarinets have stars on them. I believe that the standard model has 2, the intermediate 3, and professional four.

Hello, I actually own a professional one, and with a nice repad and tune up, it would be a great instrument. Little is known about them, although as you implied, they are rather old. If you google the makers name, robert malerne, you may be able to find more about him and his instruments, I have yet to have the initiative to do so... I know that he also designates names to his saxophone, such as master and others.