Chalcedony

67S
Chalcedony bead
1-2 century AD
Roman or Parthian

Compressed spherical body with multiple ribs. Conical hole. 
Intact, good condition. Insignificant ancient chip on the surface.

Max diameter: 20 mm
Height: 16 mm

For similar beads see:
-Alexeeva E.M. Antichniye busi severnogo prichernomoriya, Academy of Science, Moscow, 1978, table 37: 23