Appraising jewelry, where to go, what to expect, how much does it cost?

I have an antique ring given to me and would like to get it insured.
I wanted to know how much it costs to get jewelry appraised and what to expect from a reputable place.
Also, where do I look for something like that?
It is a platinum ring, but the metal is very ornate, almost like lattice all over the ring. It has a large and uniquely shaped diamond in the center with large bagette chips placed around the center. It is so old that the stamping on the inner side of the ring is illegible. Perhaps someone who knows what to look for will recognize the jewler. I believe it was created in the late 1800's and is very beautiful. I am scared to find out how much an appraisal would be, and I have no real idea what to expect.

An appraisal can be free at some jewelry stores/chains. They should be willing to do the appraisal in front of you (no swapping diamonds in the back room). Since the piece is an antique, you can call antique dealers and find out from them if they're certified appraisers or if they use someone in particular. (You may have to pay for someone like that- I can't imagine it would be terribly expensive. It is always free to ask!)

An appraisal should cost you between $25 and $50 depending on where you live. Any jewelry store should be willing/able to do it.