Look at the back of the watch case using the jeweler's loupe or magnifying glass.
Write down any numbers, symbols, and words that you see written on the back of the watch case.
Open the watch itself, from the back, using the watch-opening tool. Be careful not to lose watch parts, and not to scratch the crystal clear face of the watch while doing so. Usually, by rubbing your finger along the outside of the watch case, you will be able to feel a small notch area where the back of the watch is meant to be opened using a jeweler's watch opening tool. If you do not have or cannot find a jeweler's watch tool to use, try using a U.S. quarter coin to flip open the back of the watch case for inspection.
Look at the inside watch case parts with the jeweler's loupe or magnifying glass and write down any symbols, numbers, and words that you see inside of the watch case. Often, if the watch is 14 kt gold or some other gold karat, the weight of the gold watch case will be etched inside of the watch case.
After writing down the hallmarks, symbols, and words inside of the watch case, look at online resources and references to help identify information about whether the watch is 14 karat gold or some other gold karat quantity. If it is stamped "14k," "14kt," "14 kt," or "14 karat," then chances are it is 14 karat gold. If it is stamped "rolled gold," "RGP," or "gold plated," then it is not gold through and through, but only gold-plated or gold-filled. This does not mean that the watch is worthless, however, for it might hold some type of antique or collectible value.
If the watch is not hallmarked, stamped, or numbered, purchase and use an acid testing kit to find out whether the watch case has any gold in it.