it is actually white gold I had the same one you can either get it with a set or by itself but it is wg not sure of the karat and I think the diamond is like .10 of a karat if I remember correctly just a little to help out a bit good luck
If you will look inside the ring it will tell you what it is. Silver will be either Sterling or .925, gold with have the karat stamp, either 10k, 14k etc. Please look and let us know what it is. Thanks