This extremely old hardstone / jade bracelet dates from the Liangzhu Period (3300 BC-2200 BC).
It is a varigated black color with one spot of pale yellow green on the interior.
It is in excellent condition, even though its material has been been degraded over time (The scratch test only works on the green spot due to the degradation of the darker areas).
It also has a crystal structure that can be seen under high magnification.
It has an outside diameter of 3 1/4 - 3 1/2 inches (8.5- 9 cm) and an interior diameter of 2 5/8 inches (6.6 cm). It is about 3/4 inch in width (1.8 - 2.0 cm).
This is an outstanding piece and is similar in style to another burnt jade bangle of white chicken bone color in published works.