Your elegant bracelet is worthy of an expert appraisal. RA are the maker's initials. It could be an unregistered mark. Another possibility, but not sure, it looks similar to Robert Allison, Silversmiths, Glasgow, Scotland, UK ca. 1960s -2003.
Mehrnaz, are you able to provide an account of the history; any background information available? Apart from helping in the hallmark determination, this information will help also, in estimating the value. How did you come to acquire this piece? ie. gift, auction, jewelry store, relative?
