Tag Heuer is a brand of high-quality Swiss watches. While the company makes many lines of watches, the Calibre 17 and Calibre 17-RS watches are easily characterised by their automatic movement design. Rather than running on solar or battery power, Calibre 17 models are powered by the motion of the wearer's wrist. These watches are a few minutes per month less precise than quartz-movement watches but are still excellent and innovative time pieces.
Study the design of the Calibre 17 watch. The retail price for these watches is around £13,000. Exercise caution when considering purchasing one for a fraction of that cost as it is likely a replica.
Look for a small second indicator at the 3 o'clock face position, and a chronograph minute indicator at the 9 o'clock face position. Authentic Tag Heuer Calibre 17 watches have these features. Examine the casing around the face of the watch for polished bevelled edges and curved, faceted horns on both case sides. The watch crystal should be cut and polished sapphire with double antireflective treatment.
Locate the tachymeter scale rimming the bezel of the watch. Measure the case diameter to verify that it is 28.6mm wide. Look for the words "TAG Heuer -- Calibre 17 -- Swiss Made" and "Cotes de Geneve" engraved on the watch as an additional measure to verify its authenticity.
Request the seller to meet you at a watchmaker's or jeweller's that you trust to examine the watch for verification. Do not attempt to open the watch yourself to examine the works; this should only be done by a professional, so as not to damage the watch.