I bought mine directly from the Spigen Site our packaging does look differently Mine says for Galaxy S4 when yours doesnt?? Strange and no rainbow effect here at any angle
One of the reasons I ordered from their site and not Amazon. Seems a lot of people were getting them on there for a lot cheaper when I paid much more. Sounded a bit fishy. Knock offs run rampant.
I ordered it from the Spigen SGP seller on Amazon though. I even followed the "Find us in Amazon.com" link that Spigen has up on their website to get to their Amazon page. And just now, I went to the original.spigen.com website that is on that little black authenticity paper inside the package, typed in the serial number, and the site tells me it's a "Genuine Spigen SGP Product." So it must be real, right?. Maybe Spigen just uses different packaging sometimes.
And as far as that bluish/rainbowish tint goes, if it isn't the screen protector, it must be the screen of the phone itself. Here are pictures of my old Evo and my new GS4, both with SGP/Steinheil Ultra Crystal screen protectors. When looking at the S4 off-angle, you can definitely see that their is a blue/rainbow tone to the screen, while the Evo doesn't exhibit this.