Chalcedony is usually subject to a dye treatment which may not be permanent. Gently clean by rinsing in warm water and drying with a soft cloth. Certain stones may fade in light or heat.
Emeralds may be subject to an enhancement process using wax, oil or resin, which may not be permanent and require special care. Gently clean by rinsing in warm water and drying with a soft cloth. Avoid sudden temperature changes, steaming, chemicals and ultrasonic cleaning.
Sapphire is commonly subjected to enhancement processes or treatments such as heating and diffusion. Gently clean by rinsing in warm water and drying with a soft cloth.