Lumhechati, if/when you are sure enough that they are blue papers, the only way to know for sure is to invest the money for certification, so they would "officially" be blue papers.
You might also bring them with you to a show or bourse, where several dealers would have a blue paper in their stock and you could compare yours. Or you could buy a reference copy off of eBay
....358 can be purchased reasonably.
Anyone here can give an opinion, and you can have yours. Mine is that no amount of enhancing light is going to prove that your stamps are blue papers. You need a comparison with a known copy, or someone to see the stamp in hand that knows these issues well.
Hope this helps, Ray