I was givin a beautiful cameo necklace by a friend, the cameo came off & I can't find it, should i tell her?

yes, you must tell her if she is a friend she will understand.

Can you replace it? Once I was given a Sapphire star ring by my best friend. While on vacation I lost the stone. I knew where she got it and I bought a new one. Once my kids gave me a cheap little necklace for mothers day. A few years later I was jogging and my hand caught the chain and it broke. The little pendant was gone. I even went back and checked about a half mile radius and couldn't find it. I received a new one from them for my birthday that year.

I probably would tell her you feel just sick that it is lost. That way she won't think you are unappreciative.

First u think whether she is a good friend of u or not... and then proceed bcoz if she is a good friend of u who knows all ur emotions she can understand otherwise she might leave u by the same reason ok...

Yes, you can tell her and ask where she got it. Maybe the store will replace it.

Only if she asks.