Inner diameter is just under 16. This is a lovely bracelet with an eye pattern, and it's the type that changes color with water. Please see image 3 (o^^o). Image 3 is not the item for sale, so please rest assured that the actual product has not been put in water. Health and Healing: It is said to promote physical and mental relaxation, eliminate negative energy such as stress and anxiety, and lead to good health. Improvement of Interpersonal Relationships: As a characteristic of agate, it deepens bonds with people and supports maintaining good relationships at home and at work. Evil Warding and Protection: Since ancient times, it has been prized as a protective stone to protect the owner from negative energy. Color Change: Some individuals have a unique characteristic of changing color (color change) when immersed in water.