Cats-eye chrysoberyl

I have a client with a cats-eye chrysoberyl, and I need to do an
appraisal. The stone (measured in the mounting) is roughly round,
about 9.3 mm in diameter and 8.5 mm in depth. It is a very fine
yellowish green color, with a very defined “eye.” I am trying to
determine a replacement value for insurance.

Any suggestions?
Douglas Zaruba