Hn i never second guessed it. I had nothing. No imei or anything. I wasn't able to prove properly and chat screenshot, they are like ye kuch prove nhi karta ye koi evidence nhi hota hai sirIn your case, I guess matching the IMEI numbers was an option if you saw the listing of a new watch and asked for pictures of the watch's imei. I think it is pertinent and very important to be extra cautious while dealing online unless you know the other party.