Andrew Nethercott Antiques has dated this piece to the 1890s.
The silver mount hallmarked London 1890, makers mark B&Co probably for BEWLAY & Co Ltd

The silver collar mount inscribed Guy M Campbell
The collar mount with dents, otherwise in good sound bright condition, no splits or holes, with the original brass and iron ferrule.
The selected sample agate with natural fissures.
Diameter of agate ball 1,5/8" or 41mm
Length 34,7/8" or 885mm, weight 265 grams.
Andrew Nethercott Antiques has dated this piece to the 1890s.
Works of art, collectables, scientific and decorative antiques from the 17th - 20th century
You can view the stock and full dealer information on the Andrew Nethercott Antiques Profile Page