Nice little dirk! Turned bone handle, fits the profile of a 'gambler's dirk'. Could be European or American. Often when one sees a 'provincial' piece, we guess American, but it could have just as easily been a European blacksmith's piece. I steer away from Mexican or Spanish colonial, who also have simpler/cruder pieces, but not in this style, nor does one see scabbards with those types. Two things that (to me) point towards a possible American distinction is the way the bone grip is lathe-turned. It reminds me of some of the scrimshaw I've seen here in the states. Secondly, the diamond-shaped guard is exactly like those I've seen on so called Old Western gambler's dirks-