This is a 40 mm x 30 mm oval carnelian cabochon.
Carnelian is a natural stone that is heat treated to bring out its beautiful burnt orange color.
Carnelian is a member of the quartz family and measures a 7 on the Moh's scale of hardness, making it suitable for all types of jewelry applications.
Photo is a representative sample. Each cabochon will have its own unique markings.