Cats-Eye and Star Alexandrite
The term cat's eye, or chatoyancy, is used to describe a phenomenal optical property in gemstones, in this case chrysoberyl. The effect, when present, appears as a bright, narrow slit similar to the pupils in the eyes of your favorite feline. This phenomenon is caused by parallel fibrous or needle-like inclusions oriented parallel to the C-axis that interfere with the passage of light throughout the crystal, scattering and reflecting light back to the viewer as a thin line. They are found in Brazil, India, Madagascar, Sri Lanka, and Zimbabwe. Chatoyant chrysoberyl is particularly incredible because it exhibits two rare phenomena: both the cat's eye effect and color change. The star variety of alexandrite is extremely rare, and it is found in India. It displays a 4-ray star that is due to hollow tubes within the stone.
Cats-Eye and Star Alexandrite Classification
||Cats-Eye and Star Alexandrite |
Cats-Eye and Star Alexandrite Characteristic Physical properties
||Natural cat's-eye alexandrite typically has fine needles or hollow tubes. The stones can have fluorite, apatite, mica platlets, rutile and multi-phase inclusions along with negative crystals, liquid and fingerprint inclusions. Some stones might show twinning. |