Have ordered some batteries from china for a couple of bucks that said were genuine. when charging one didnt charge at all and the other one dropped in the n900 from 40% to 0% in 1 minute every charge. both have the exact same holographical stickers on them as the genuine one. So these stickers wont say anything about the genuine of a battery. The codes on a BL5J cant be checked on the nokia website. when entering them it says that you need a 20 digit number. Wich the BL5J obviously does not have!