SW will be the maker's mark. There are quite a few SW makers, however. Are the initials inside a crown or next to a crown mark? Are the letters next to each other or is the S above the W? Do you have any idea about the age of the piece? Any background Information? The plus sign is puzzling and will take quite a few hours of further research, complicated further by the absence of an image.
You might like to consider a Paid Opinion considering these marks....
The Bracelet sounds like a quality piece Robert, and as it's comprised of gemstones should be appraised in-store.
