I recently obtained a Smith & Wesson 32 Double Action, tip up revolver (1880 to 1919). It is nickel finish with Mother of Pearl grips (grips have brass S&W logos). The seriel number is 2318XX.
If it's double action, then it's not
a tip-up, it's a top-break. The terminology is confusing because the cylinder
of a top-break does indeed tip up; however, on a proper S&W tip-up, the muzzle end of the barrel
tips up. The hinge is located above the forcing cone. FWIW the tip-ups were all SA, and the .32-caliber variants fired the now-obsolete .32 Rimfire cartridge.
Now about that top-break...
If it has an external hammer, it's a .32 Double Action 4th Model, built 1883-1909. If it has a concealed hammer and a grip safety, it's a .32 Safety Hammerless 3rd Model, built 1909-1937; this gun was also known as a New Departure, or a "Lemon Squeezer" in popular slang.
As with other S&Ws dating from this time period, they were often built out of serial number order, so the only way to verify the actual age is to get a letter.