Hi-
I really dont know how they marked thier items, just know that they used the Llama, which makes sense. The .900 is the purity mark of 900/1000 just shy of sterling, called coin silver here in the U.S. see:
http://www.925-1000.com/silverglossary2.html" onclick="window.open(this.href);return false;
The "J" is probably the makers mark, I do not believe that they use date lettering. Hopefully someone else here will be able to help you further.
Best wishes- Byron