Rolex dive watches are incredibly popular - selling thousands every year. But if you want the rarest of the rare dive watches, you need to know about a small French company, COMEX. Founded in 1961 to explore the depths of the oceans, COMEX is the NASA of the deep sea. From 1970 to 1997 COMEX worked closely with Rolex, and COMEX divers were issued with Rolex watches - helping Rolex to engineer their famous gas escape valve. The COMEX models had one small difference that sets them apart.