Impossible to answer- value depends on make, model andcondition- and with some guns, we can only make an educated guess.Jean Marie Prosper Schlemmer was a gun maker in Liege Belgium inthe 1925-1935 time period. He died in Liege in the 1950s. The veryfew Prosper Schlemmer guns I have seen were nicely made, but soscarce that it is difficult to find comparable sales. You will needto visit a knowledgeable gunsmith or gun show in your area for ahands on appraisal.