Antique Mirror and Comb Set with 3 hallmarks Please See

[adamg816]

Hi needed some help in identifying these hallmarks, they are on an antique sterling mirror and comb set.


(I apologize for the images being upsidedown)
The first mark is "4212"
Then marked "STERLING"
Then the last one I am having trouble with looks like "JS" with a split rectangle that runs thru the middle of the letters. Or it could be an "E" enlongated that runs thru or an "E" and another letter(s) that run thru.
Really hard to tell. Would love to hear from everyones ideas or knowledge regaarding this piece. Here is a photo of the piece the mark is on.



Thanks for any and all help in advance!

Best Regards-
Melissa