Chalcedony
Chalcedony was a treasured gemstone of the ancient world. No important Roman would be without a seal, amulet or signet ring carved in this fine and durable material. The Victorians, too, prized chalcedony for carved cameos and intaglios: its fine texture allows for delicate and intricate workmanship. Jewelry designers today love its glowing translucent tones and its availability in a wide range of colors and shapes, including carvings.
Durable and easy to care for, chalcedony has a hardness of 7
-Source AGTA