I bought the pair and received them within 5 days. The earrings only come in a basic box and a packing slip (no appraisal).
I went to a local jeweler and he estimated that the earrings were a shade under 1/2 carat, one diamond was better than the other, the other diamond having some more inclusions, both rated in the H-I color range, and rated I1 for inclusion range. He thought that the value should be around $650-700 or so.
Since i paid $500, I think this was a good value. He thinks that the overstock.com range of S1-I1 is too wide and can greatly influence the value of the diamond (i.e. you're more likely to get the bottom of the range). He also said that the earrings should be much more similar to each other, in my case it is not.
To my naked eye, they look fine. A little small but in my girlfriend's ear, i'm sure they'll look proportional. I used an online coupon that shaved 10% off my purchase. I suggest searching for coupons prior to buying.