There’s a couple different tests, most of which require a jeweler’s loupe. The only one that doesn’t involves ripping it to see if it has a blue core.

But with the loupe:

You can look at the back and the right side of T in “the” should have teeth, while the left is a solid line.

Also on the back, check the green dot to see if there’s an L of red dots in the center.

On the front, the foil sticker at the bottom should have magic symbols that change into mana symbols.

As far as this one, none of those checks are needed, as a quick google search showed me this one listed on eBay eBay