The letters look to me like S over E (possibly) and P so very likely meaning electroplate. However the mark are not very clear. Can you clean them out and post a new picture please. It might also help to see a picture of what the marks are on.
βThe letters look to me like S over E (possibly) and P so very likely meaning electroplate.β - a reasonable clue, so we are missing the letter βNβ to complete the set.