Well, I'll say I'm not an expert on this card. Here's a high res image of a known good card. You can easily see the border should match the color of the clouds.
Here's yours for comparison.
Buy a couple of commons from the set online and then compare them. Make sure the paper has the same feel, gloss, stock, smell, etc. Basically, be more sure before you pay a $100 or so to try to authenticate.