What is the significance of an engagement ring? To me it says, "I'm getting married".
It also means "could be thinking of starting a family soon / coming off contraception" - I hate to be so blunt, but that's just the way the unofficial HR policies of some of the offices I've worked at have been.
In the worst case IME, the grad job i took out of uni was actually a rather nice place to work for - (actually it was my 2nd out of uni job, because i ended up in a company which was a horrible place to work for before quitting, nothing to do with sexism, it was just horrible working practices, and i don't count it mentally as "my first real job there).... i ended up staying for many years in the place with my female boss who had the questionnable hiring practices.
that was the same dept that ended up firing a female employee because she couldn't get her act together with working from home and childcare (a long story in itself, and one where i personally (privately) sided with the employer because she was just taking the piss)
So yes, aside from the initial
of hearing her thoughts on female grads off the record, actually it wasn't a terrible place to work in practice.
I know that sounds odd, because it's easier to paint someone who's weary of hiring "settling down age females" as the devil incarnate, but, it isn't as black and white as that.
Hope that answers your Q, blueshoe :) For the record I will be advising DD to ensure she takes off her wedding ring/engagement ring in 10 years when she's out of uni and looking for a job, if she has one/goes for a career path where this thing crops up. It's immensely sad, but I'd rather give her a realistic idea of the world rather than telling her how it should be/ how I hope it is for her 
To give another example, I've never experienced salary gaps (to my knowledge) in any office where i've worked, although my role is more "output focused" than some office jobs, which perhaps enforces a certain level of accountability when it comes to auditing a co. for wage gaps. Harder to prove outright discrimination doesn't go on , if it's in figures/etc.