Ruby crystals within coarse-grained rock of green zoisite with black amphibole crystals. While ruby has a hardness of 9, excellent toughness and very good stability, zoisite is brittle, only has a hardness of 6 and fair to poor toughness – suitable for earrings but care should be taken when working with and setting the stones.
Hardness – resistance to scratching and wear
Stability – resistance to alteration by light, heat or chemicals
Toughness – resistance to fracture, cleavage or cracking
Please note you will receive the stones in the photograph