Types of inclusions in the Ural demantoid
1. Bissolite fibers or hollow channels in the stone.
1a. "Horsetail" with the center of growth inside the stone
1b. Approximately parallel distribution
2. Artificial cracks due to the imperfections of production and poor quality of heat treatment
3. Natural cracks filled with limonite (aqueous ferric oxide of red color)
Bissolite fiber and hollow channels - this is the famous "horse tails." Hollow channels create the effect of a cat's eye.