It's a mid/late 50's model, probably a 2852 (?) with a caliber 50x (501 or more likely a 505) inside.
Nice watch Your Grandfather had very good taste and that dial has aged to a lovely hue which looks great with the, I think, rose gold hands and markers. The case looks in fine original vintage shape too, although a bit grubby. I would have it serviced by a good watchmaker fluent in the sympathetic handling of vintage watches, specifying that he not polish the case or do anything to the dial and hands and enjoy it for the rest of your days.
Welcome and Gramps certainly had good taste. I believe you're about to learn a new term :"Dibbs". However I would strongly recommend that you have it serviced and cleaned only. No new parts or polish. Then wear it in good health ;-)
I'd put it a bit higher in value, in the $1K range; very nice, looks unpolished, nice pink gold markers and hands. I'd put it on a nice exotic strap though, after a service, and ditch the stretchy bracelet!