Are there any markings inside to let you know the metal, or a maker's mark? Otherwise a jeweler should be able to test to see what metal the ring is made from. They might be able to give you some information on the stones as well... not sure if they'll have to take one out of the ring though (?).
Looks like an antique cluster style ring or a cocktail ring in yellow gold, you need to take it to a jeweller and ask them to estimate the size, colour, clarity and total weight of the diamonds and determine what the metal is - 14K 18K or whatever and they should also be able to give you an approx. idea of what it is worth.