The “AMERITH” inscription on the celluloid handle of this letter opener refers to the Amerith Division of the Celluloid Manufacturing Company, active 1928-1935.
A pocket knife with two blades made of ferrous metal. A sheet of cream celluloid is attached to each side with rivets. There is no maker's label, but the knife was likely a souvenir from the coronation of King George V or King George VI of England. It reads "Coronation Souvenir" and bears the image of a crown with a G and an R on either side. "GR" could be the royal cypher of either king, as it stands for "George Rex."