Just checking here: are you aware that they are worth more than the bitcoin on them as long as they are unredeemed?
I have seen them go for 3 and more btc on auctions (having 1 btc on them).
DO NOT OPEN THEM seriously shorena is giving you the best advice you could have. If they are not redeemed you just got very lucky if you bought for the face value, there is a big collector market for them.
If they look like good quality look into the graded ones. There are 2 main companies that do it. But if you have a high grade coin it goes up even more. So really your very lucky. If I got one unredeemed I would get it graded then go to btc market on here. Or if it appears not to have decent grade go straight to forum and not waste money on grading.