1. In contemporary watches, look for complicated models, limited production, and top brands such as Patek Philippe, Vacheron Constantin, Audemars Piguet, Breguet, A. Lange & Söhne, F.P. Journe, Richard Mille, and Greubel Forsey, says Aaron Rich, Sotheby's (BID) department head of watches in New York.
2. Vintage watches, by definition, are scarcer. Top brands such as Patek Philippe and Rolex are known for increasing in value.
3. Patek Philippe's stainless steel models from 1940s and 1950s make good investments because they were not popular at the time and the company produced few of them, says Michael Ashton, whose Madison Avenue boutique in Manhattan specializes in vintage Pateks and Rolexes.
4. Make sure to keep all original documentation, certificates, and accessories intact. Take care of your watch's original condition, but don't restore it—or even change the strap, If you do, it will go down in value.
5. Buy what you love, even if you buy as an investment, says Roberto Chiappelloni of Manfredi Jewels in Greenwich, Conn. "Don't buy something just because it's on sale or because it's the newest, craziest thing," he said. "You will wear it day in and day out for the next 20 years."
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