Tagua nut. Amber, mother-of-pearl and wild boar fang inlay.

See completed netsuke here.

 
 
Monkey netsuke in progress Monkey netsuke in progress Monkey netsuke in progress Monkey netsuke in progress Monkey netsuke in progress Monkey netsuke in progress Monkey netsuke in progress Monkey netsuke in progress Monkey netsuke in progress