How can I check the originality of a battery buying from e-bay?
You can't.
You can look for a seller with 100% feedback or damn close to it, who has been on ebay for at least two years, and you still take your chances. There are a lot of counterfeit and relabelled batteries out there. First time I bought an eBay "genuine Motorola" battery, it turned out to be a standard battery with an "extended" label added on top of the original one. I figured that out a year later when the battery was going bad too soon--and the seller was already gone and out of business.
All you can do is look at their track record.