TAG Heuer watches are upscale and expensive because the watches last for years. A vintage watch will keep running, as long as it's maintained properly and has a working battery. Unfortunately, these older watches are often replicated and reproduced because the timepieces are worth a significant amount of money. Looking at the watch carefully will help you determine if it's an authentic watch or a worthless fake reproduction piece.
Turn the watch over and look at the back. The serial number should be clearly shown on the watch, either above the logo for more modern watches, or underneath the logo on older watches. If the watch lacks a serial number or it's imposed over the logo or inside the logo, then it's a fake.
Read the serial number on the watch. TAG Heuer watches have a six-character serial number made from a combination of letters and numbers. It typically has two letters and four numbers, but could have three numbers and three letters. The letters always go before the numbers. Vintage watches might also have six numbers, with no letters.
Examine the engraving on the back of the watch. TAG Heuer watches have quality engraving done that won't wear off or wear down, like with inferior watches. If the engraving on the watch is close to the surface or looks rubbed away, then it's likely a fake.
Look at the price of the watch, especially if purchasing the watch online. Authentic vintage TAG Heuer watches sell for well more than £325, even if the watch isn't in perfect condition. If the watch has a price that's too good to believe, then you might have a fake on your hands.
Check the inside face of the watch. The face of the watch should have crisp printing without any runs or fading. Fake watches have printing that looks a little off or fuzzy because of the cheap ink. You might also see glue left behind on the face or sticking through the face on a fake watch.
Consider taking the watch to a repair shop and asking for help. A professional knows whether it's real or fake just by removing the back and looking at the construction of the watch.