Miller shell chair label  

Just found they have a Zenith circle stamp.

Yes, there are numerous detailed discussions of this topic to be found here on this forum's archive using the search function and relevant search terminology.

Cute set. Good luck!

I did look through those posts first, just wondered if there was a way to determine the date if there is no date stamp.

If I'm not mistaken, patent numbers can be cross referenced to determine date of issue, thus ruling out prior production. That, combined with details such as painted bases and whether or not they are original (they look to be) might help to narrow down a range.

There is a lot of info out there to dig through if no experts like Eameshead respond here. But I'm not sure that anything beyond knowing they're Zenith will help much except to maybe satisfy your personal curiosity. Condition and color count more toward value with these mid-range editions.

Thank you for your help

Not much, I know and apologize for that. Too bad Eameshead hasn't been too active here, lately. He's The Man when it comes to these things and, typically, would be more helpful.

Best of luck!