Button, 23rd Regiment Bengal Native Infantry (1855-1857; plus re-raised from 27th Bengal Native Infantry, 1861-1864, later 23rd (Punjab) Regiment of Bengal Native Infantry (Pioneers) 1864-1877) , 23rd Bombay Native (Light) Infantry (1855-1877).  
French circle and dot, '23' in centre, wreath around.  No rim, brass.  Reverse marked Smith Kemp & Wright Birmingham.  
Collection of 21 buttons marked Indian Infantry Other Ranks. 
From the collection of Maj H G Parkyn.