New to the site, need help with model ID

[seattledan1]

Hey guys, I'm new to this site. I'm pretty sure that you get a thousand people a week asking for help in watch identification. I've used the search function a bunch, and researched through google for the past week, but can't seem to get any solid info on this watch. I have read that rolex was selling models labled as simply oyster or chester in Canada in the 1930's and I suspect thatis what I have. Here's the info:

The crystal is raised way above the case, and fairly scratched
The face says "OYSTER" on top and "CHESTER" below
The back says 21038 and 4453
The pin unscrews slightly that extends for winding and setting
The watch appears to keep perfect time

I haven't opened the back, because I lack the proper tools and am hesitant to take it to a jeweler without having a better understanding of the value and appropriate methods for care and restoration.
I got this watch in a large lot of watch repair tools. There was another 14K 1920's Gruen watch in the lot, so I know that this person did have some higher quality items.

Please let me know what you think, I apologize in advance for my lack of knowledge on this subject.

[joe100]

I believe those were branded Tudor. The serial on the caseback looks Tudor to me.

[seattledan1]

I should probably get the case opened to look for the Tudor marking then. Will the watch lose value if I have the crystal buffed out?