Norma, how much your cameo lovely is worth really depends on a number of factors, and the quality of the craftsmanship is one of the most important.
Then one need to check the condition of the cameo for any cracks or hairline fractures or chips. You need to examine this carefully with a hand lens.
The size of the cameo, the subject, the metal surround, if it is mounted, and the material your cameo is made from are all taken into consideration when the appraiser examines and values a cameo. If you are considering an on-line appraisal images will be required.