Blue Cat’s Eye
The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.
Blue Brazilian apatites and those with a “neon” blue-green color, similar to that of Paraíba tourmalines, command the highest prices. Rare, rich purple specimens from Maine are also highly prized.
Since apatites are relatively soft stones, skilled faceters can add a premium to their value with exceptional polishes.