Rock crystal

273S
Rock crystal bead
1-2 century AD
Roman 

Spherical body with conical hole. Slit at one end.  
Clear with planar inclusions. Intact, good condition.

Max diameter: 18 mm
Height: 17 mm

For similar beads see:
-Alexeeva E.M. Antichniye busi severnogo prichernomoriya, Academy of Science, Moscow, 1978, table 35: 24