Have you asked her? Even if you’re keeping it a surprise you could bring up movements in the context of your watches and see what she thinks
Watches
A community for watch & horology discussion.
Citizen makes some nice ladies watches with the eco drive. I got my mom one that looks really classy.
If you are in the US you could take a look at the officialwatchdeals store on ebay and get a citizen eco-drive you like from there. I don't think you can find them for less anywhere elso.
If it´s expensive, mechanical. Shame to waste precious metal and gems on a quartz. If your budget is over €500 I´d go for a mechanical watch. If under, quartz if she will wear it on occasion only.
https://www.tissotwatches.com/en-en/t0581091104100.html
Small, beautiful feminine watch. Even better with a blue strap.
Quartz, definitely. Most people who aren't really into watches will not want to deal with setting the time. There are a ton of really nice quartz options available. Check out Tissot and Citizen to start.