www.925-1000.com

Hello guys,
Can anyone help ID this one?
to me it looks like "RM" but could also be "RRM" or maybe the mark was struck twice not on the same spot.
Could this be 16-17th Century?

Thank you!

Not 16th or 17th century. Looks to me more like a relatively recent pewter version of a seal top. If it is silver, the disc of the seal top is not where the maker's mark would be. It is where the owner might put his (or her) own mark - normally initials. Your RRM is perhaps meant to represent such initials within an armorial shield, which again seems to me more 20th century than earlier. Sorry if this is a bit disappointing.