Looking for advice on a vintage Globemaster

Hi everyone,

I'm helping my parents downsize and clear out their house, and came across a vintage Omega Globemaster that I'd like to learn more about. I have some knowledge of vintage and antique jewellery, but very little experience with watches. A preliminary Google search suggested this might be of interest to collectors, although I'm aware that Google's AI can be overly optimistic about these things. I'm hoping members of this forum can help me understand its potential value and whether it's worth selling.

I'm attaching a few photos. I have no case or documentation, just the watch itself. The caseback markings indicate a 10K gold-filled bezel with a stainless steel back. The bracelet has 10K gold-plated tops and ends, with stainless steel bottom caps.

Based on my preliminary research, I believe it dates from the 1950s or early 1960s, but it hasn't been properly identified or authenticated. As I understand it, determining the serial number would require opening the watch, which I'd leave to someone qualified.

The watch appears to be a mechanical, hand-wound model and runs when wound, although I have no idea when it was last serviced. It's also been sitting in a basement, unworn, for probably a few decades.

I'd appreciate advice on the following:

1. Can anyone confirm its approximate age and whether it's a desirable or collectible model? Is it rare or relatively common, and what would be a realistic ballpark selling price?
2. Would you recommend having it authenticated or inspected by a watchmaker before selling? Is servicing necessary even if it appears to be working?
3. Is there anything I can check myself to help assess its condition and value?
4. If it's worth selling, are there any online platforms you'd recommend? I'm in a fairly blue-collar city and suspect Facebook Marketplace might offer a limited pool of potential buyers.

Any other advice or information I may have overlooked would also be appreciated. Thanks in advance for your help!

From your photos, it looks like

“10K GFD bezel, stainless back” with the star mark and a plain back is a US-cased Omega: Swiss movement, case made in the US for the American market, late 1950s to 1960s. Gold-filled US-cased pieces usually sell for less than Swiss-cased steel or solid-gold Omegas, and Omega rarely lists them in its online database. The Speidel band was likely added later.
The dial has some spotting, and the hands look darkened. Leave both as-is; buyers prefer original over refinished. Check whether the crown carries the Omega logo, since a plain crown is likely a replacement.
The caliber number on the movement settles the age. A watchmaker can open the back and photograph it in a few minutes; then post it here, and people can date it.
Running isn’t the same as healthy. After decades unworn the oil will have dried, so don’t wear it daily before a service. If you’re selling, many buyers prefer it unserviced and untouched.

Thanks so much for your response. Its really helpful.

No crown on the dial; so I guess a replacement. I imagine that brings down the value a bit?

Do you have any sort of preliminary idea of how muc $ I might be able to get for it? As is, unserviced and original - not refinished? Or do you need the caliber number to determine that?

Ill take it to a watchmaker sometime this week and add the photos to this post.

Thanks again