Cat's Eye Apatite
Very rarely, apatite cut in cabochon will display an unusual optical effect called chatoyancy - otherwise known as cat's eye.
Cat's Eye Apatite is a very rare gemstone indeed. Of the many varieties of apatite available, only a handful of any particular yield will possess the properties associated with chatoyancy. Chatoyancy, better known as cat's eye, is an optical effect created by an inclusion within a gemstone. The result bears a strong resemblance to the reflection of light within a feline's eye. In the case of Cat's Eye Apatite, the effect is produced by inclusions of rutile crystals within the apatite gemstone. Only gemstones that are finished in cabochon are able to create this effect, as it is necessary to make sure that the rutile inclusion aligns in a particular fashion to produce this stunning effect.
Cat's Eye Apatite will always be cut in cabochon, as that is necessary to preserve the cat's eye effect. To provide the largest sized stone most will be cut oval-shaped. Round and pear-shaped cabochons will also be utilized, though they are much less common to see. The value of the gem will primarily be determined by the strength of the chatoyancy present. The intensity and saturation of color will be considered second, unlike in normal colored gem grading, where it is the primary factor in determining value. Cat's Eye Apatite may be found in any color that apatite might be found in, with pink, yellow, green, blue, and violet being the most standard colors available.
• Physically, apatite is believed to help strengthen particular areas of the body, including cartilage, bones, and teeth.
• Some healers also suggest that apatite can help ease aches and pains within a person's joints.
• On a metaphysical level, apatite is thought to stimulate creativity and encourage extroversion.
In theory, it's possible that any location where apatite is mined could potentially produce Cat's Eye Apatite. In practice, however, only a few places around the world reliably provide this gemstone. Brazil is a leader in providing gem-quality apatite. Other locations across the globe supply this gem, including Madagascar and Sri Lanka.
• The word chatoyancy derives from the French phrase æil de chat, literally meaning "cat's eye."
• The cat's eye is a similar phenomenon to asterism, which is an inclusion that creates a star-like effect across the surface of a gem.
• Green or yellow apatite gems are the most likely to display instances of chatoyancy.
• The cat's eye is best viewed under direct lighting. As the stone is rotated, the effect can be observed to shift across the surface of the stone.