This is a tailor's square. Probably a suitmaker owned it.
They are showy and beautiful, and I love them. This particular one is a real pip.
But they don't have a high value. About 30-50 is what I've seen people actually pay in money.
I've seen some priced higher than this, but the ones that actually sell go in this range.
The 1 foot 4 fold caliper rule is better than average too. Its got a decorative center joint, always a good thing. Who made it?
yours Scott