What does “NOS Part” mean?

A NOS part is new old stock: a genuine part made by the brand some time ago that was never fitted or used. It might be a bracelet, clasp, dial, bezel insert, crown or hands that sat in a watchmaker's drawer, a retailer's stock or a parts supplier's inventory for years.

NOS parts are especially valued for vintage watches, where current service replacements may look different from what the watch originally had. A period-correct NOS part can restore a watch's originality in a way a modern part cannot. The difficulty is proof: claims of NOS are common, and some parts are reproductions or used parts cleaned up to look new. Buyers look for original packaging or labels, part numbers, period-correct markings and the absence of wear, and they buy from sources they trust. Fitting a NOS part should still be disclosed, since the part was not with the watch from the start.

Typical usage: “NOS Rolex crown for a vintage Submariner, still in original sealed packet, part number on label.”