Hi thanks for writing in. Even from the image, you can tell this is a quality cameo. The condition will be all-important for appraisal purposes. The art of gemstone carving was known in ancient Greece and Rome and revived in Renaissance Italy, when connoisseurs began to form rich collections of engraved stones. Shell cameos, which were cheaper and more easily worked, became fashionable in the 19th century.
Are there any inscriptions anywhere, roman numerals, numbers, letters, that you can see, anywhere on the cameo, carefully examine the cameo and the reverse, hold cameo to the light and also examine statuary for any clues.
You need to measure the dimensions of the cameo and the statuary, separately, determine the condition of cameo. Are there any cracks, chips, hair line fracture, hold up to the light for this.
How did you come to acquire it? Is there a history of provence? All the above factors will help the expert to appraise and value this marvelous item. A real work of cameo art!