Can i have your opinion?

Silvertone is certainly a bad idea. The first one was very nice, but it really depends on your friend. The last one really stood out as somewhat gaudy "S!" whereas the fifth was quite elegant. They are all nice, and it is very thoughtful of you to get your friend a necklace. But it really depends more on your friend's tastes than ours...or yours. I would go with the first or the second to last, but that is simply my taste. You know your friend, and we don't...whatever she would like it what you should get. :) I'm 20 years old.