The handle could be ivory, the collar looks like its influenced from the arts and crafts movement around the early 1900`s. its certainly influenced by William Morris designs .by the looks of it but it needs cleaning to lift the detail, The shaft is influenced by Africa and would have thought that its English made but maybe the shank was decorated in Africa whilst the gentleman was over there. If the collar was cleaned it would tell you more about the metal used as not all silver had hall marks on which suggest its not European . You could try using methylated spirits on the shank it may clean it up? and a good metal polish for the collar using a soft cloth. The other possibilities is that it was done by a seaman using walrus tusks and the other influences used during his travels? a lot of options , if you look up family heritage it may give you a clue as to the what the person did during his lifetime which may give you some idea its a lot easier to do on the computer.