This is a engagement/wedding band, but could also be a cocktail birthstone ring.
It says 925 on the inside of the band. I've come to learn this normally mean's it's about 92.5% silver. Because this stamp is on a gold color ring, this probably means that the ring has gold plating added to the outside of the ring. This plating is still in very good shape. It hasn't worn down.
I'm pretty sure these are real sapphires in the ring*, but I'm not positive about the 16 baguettes diamonds embedded. They look like real diamonds, but it's possible they are a crystal look a like. There are 8 of the sapphires. It's a high quality ring and uniquely designed.
Next to the 925 stamp is a large M with a tail on it and then RF. I think these are the initials of who made it/designed it, but possibly it's a jeweler's meaning for something. I'm just not sure, still learning all of this. Because I'm not positive about the diamonds I'm going to say COULD Be and not say "it Is". I don't want to be in accurate in my description. I'm going to lower the over all asking price because of this uncertainty.
When I put this on my ring sizer it says it will fit a size 8 finger.
*I'm not an authority on jewelry or rings. I'm just learning. The statements I'm making are my best guesses. I try to supply many pictures so people can see the same things I'm seeing and make their own judgements based on this.