When purchasing a pre-owned luxury watch online, any timepiece aficionado worth his Datejust is familiar with the perpetual nagging question: “Is this thing the real deal?” For true peace of mind, allow us to suggest that you look no further than eBay. Yes, eBay. The time-tested online marketplace not only features crazy deals on literally tens of thousands of watches from every major house of horology (from Rolex to Patek to TAG to Omega), but now also offers their very own ironclad Authenticity Guarantee. Professional authenticators use state-of-the-art equipment over dozens of inspection points to verify a watch’s legitimacy, at which point each timepiece receives a unique authentication card with detailed information about it. So you can shop secure in the knowledge that whatever wrist fodder catches your eye, it is in fact the real deal.