need a id on a ring

[jeff0172]

i purchased this and the seller said it was bought 25 years ago at a jewlery shop and said it was 925 silver but it looks to me like it says 526 but i am not sure what any of the markings mean any help would be greatly apprectiated the seller said it was gold plated silver but if it was wouldnt the plateing ware off after 25 years?
http://i939.photobucket.com/albums/ad237/jeffisdabomb_2009/KGrHqQOKjwE2LgMfPY5BNwr6ZnGgg_3.jpg
(admin photo edit - images too large - link only - see Posting Requirements )

[jeff0172]

sorry if there are any errors in the posting this is my first post