sounds like it means it's 18 K gold....and the maker is R. P. M.
But 18 K would be unusual for a bangle with a chain guard...too soft, the chain would break and the bracelet would bend. So I think it's some sort of Metal Plating....but I can't figure what the R stands for.
that's a guess....knowing where you got the bracelet and how old it is would also help.
Linda c

Thanks, Linda. I thought metal plated when I saw the M.P. part, but can't figure out the "R" either. It belonged to one of three deceased relatives, one died in 1970, one in 1983 and the other just this year. I'm sure it's at least 20 years old and could be as old as 100 years, although the style looks contemporary. The surface is flat and the design is an elongated x repeated around the entire surface.

Dpoes it open with a slice sort of mechanism?

My mother had (and I now have) a set of bangles that were her mother's/aunt's/grandmother's gold bracelets and one of them is extremely soft. So much so that the clasp has trouble staying closed, and it is dented and slightly distorted. My mother lost that one and found it over a year later, driving by a friends house she saw it in the grass at the edge of the road. This one is circa 1905 (dated and monogrammed) and looks extremely contemporary. Her grandmother's are so tiny that only child can wear them now, although we have a picture of her wearing them as an adult.

Yes, it opens with a slice sort of mechanism, similar to some mechanisms of today, but it doesn't have the kind of hinged piece for security that some of today's gold bracelets have, only the chain.

I finally had a chance to take it to a jeweler and was told that RMP means "rolled metal plate." He can't figure out why it also says 18K because there's no 18K in it.

RMP Royal Mounted Police? Is this a Canadian piece?