Manufactured in 1957, this is a superb example of the International Watch Company’s (IWC) iconic “Ingenieur” Ref. 666AD, featuring the in-house Caliber 8521 and a rare black gilt dial in excellent condition.
Among the already scarce black dials, this piece stands out for its particularly rare "stepped" black gilt dial. Seen on models equipped with Cal. 8521 or Cal. 8531, the date window is uniquely positioned closer to the center, and the dial itself features a stepped construction—flat at the center, with a recessed outer section starting from the date frame to the edge.
The overall preservation is excellent. The rare black gilt dial retains an iridescent oil sheen across the surface, adding to its allure. Included with this collector’s piece are the original period bracelet (marked 2/58, suitable for wrist sizes up to 18.5cm) and the IWC archive extract—making it a true collector’s item.