There have been cases of American gunto owners wanting to reunite a Japanese soldier's sword with his family, but unfortunately the law makes that almost impossible. Since the mass-produced gunto have no artistic value, the Japanese government classifies them as weapons. If the sword is in Japan it is definitely a nihonto. If you can't do these things, it's still not very difficult. If you can read Japanese and know how to open the grip, the signature on the tang (the part of the blade inside the handle) will tell you exactly what it is. Telling a gunto from a high quality blade is usually easy. Although some gunto were either handcrafted or partially handcrafted, most were assembled in factories from standard bar stock. (meaning either 'saber' or 'service sword') were the swords of Japanese WWII officers. While being able to properly appraise a sword can take a lifetime, fortunately, you can see what makes a sword unique just by knowing what to look for.
Japanese swords are works of art, but to the untrained eye one isn't much different from another. Japanese sword, we couldn't do much more than hold it cross-eyed and bleat out 'nice sword.' Why some consider a Masamune on par with a da Vinci eludes us.
For most of us who get the chance to handle a finely crafted nihonto 日本刀 ( にほんと )