NOS stands for "New Old Stock." When a watch is described as in NOS condition, it refers to a timepiece that was probably put away for decades and has never been worn. However, over the years, it may have been passed from one collector to another, but as long as the new owner keeps it unworn, it can continue to be described as NOS. It may have been tried on just like those display pieces in a watch shop. But one thing is for sure is that a NOS watch is not mint. Most have been put away without protection (such as inside their original box), so expect the case and crystal to show minor light scratches here and there. Some will naturally patina or produce age spots depending on the dial material or type of luminous/paint applied on the dial and hands. But, at the end of the day, a NOS watch's condition will differ from a used piece in pristine condition or a timepiece with a case polish. A long-time collector will be able to differentiate them apart.
 
Here is an attractive vintage Eterna-Matic gent's watch. Stunning factory original finish dial in excellent condition—fully serviced Eterna calibre 1426 automatic wind movement with serial number 4196992, dating this timepiece to 1961. Original acrylic crystal in excellent condition—original signed crown. The case is made of gold capped over solid stainless steel and is in excellent untouched condition; of course, it is a NOS watch, after all, so do expect light scratches here and there. The case model is 3991279 and measures 34.5mm in diameter, excluding the crown by 42mm from lug tip to lug tip. Original plastic case gasket. It will come with a brand new 18mm genuine leather strap since the original was missing. Has the original buckle and tag. Will also come with its original box. The wrist size in the photo is 6 inches.