Silver Figaro Necklace from Italy with unknown Hallmark

I have this mens' or womens' Figaro sterling necklace from Italy, actually for a long time. Last night I saw something I'd never seen and hope someone can tell me what this Hallmark stands for. I think it's a circle with the M over it???

Funny how that works, all of a sudden you see something that's been there plain as day for the first time!

I've added the photo of the whole necklace, like I should have done in the first place! Hopefully, someone will know by seeing it this way.

I'd really appreciate any help you can give.

Thank you, thank you!!!