Why collectors look for one small dot

The Omega Speedmaster is a watch with a stopwatch built into it. Around its face is a numbered ring that can turn an elapsed time into an average speed. That scale is called a tachymeter. On early Speedmasters it also contains a small feature that collectors use to help identify the watch's parts: the position of the dot beside ninety.

It is easy to miss. On one version the dot sits above the number; on another, beside it. Collectors shorten the first description to DON, for “dot over ninety,” and the second to DNN, for “dot next to ninety.” Neither arrangement changes how the stopwatch works.

An old detail, on more than one generation

Some early examples of reference 145.022 have a period-appropriate DON bezel. A 145.022-68 catalogued by Sotheby's, made in 1969, is one documented example. Later versions of the 145.022 used the dot-next-to-ninety design. A long-lived reference can therefore contain more than one correct factory arrangement.

The later 3570.50's factory-era bezel is dot next to ninety. Fitting it with a DON insert does not uncover a rare original version; it changes a part. Omega subsequently returned to a dot-over-ninety design for the modern caliber 3861 Moonwatch. The mark that can help date an older watch is also a deliberate feature of a new one.

That is why the dot alone cannot establish age. The reference and its production period come first. Then the dial, hands, movement, case and bezel need to be considered together.

Old is not the same as original to this watch

A bezel can be genuinely old and have been fitted last year. A replacement insert can also have been installed during an ordinary service, without any attempt to deceive. These are different histories, and a listing should say which one its evidence supports.

A caseback suffix helps identify a version, but it does not date every part now attached to the case. An archive record may document production or delivery; it cannot by itself account for later repairs. Service receipts, earlier photographs and specialist inspection may answer different parts of the question.

What would justify paying more?

A price comparison needs two genuinely comparable watches. A period-correct bezel on one does not cancel differences in the dial, hands, case condition, bracelet or documents. An attractive asking price for another DON watch is not a record of what anyone paid.

There is no fixed premium we can honestly attach to the three letters. A buying brief needs to identify the configuration, evidence and limits behind its advice. A reviewed House opinion is labeled separately from comparable sale results; neither supplies a universal price for a dot.

For someone who wants an early configuration, the correct bezel is a useful part of the search. Someone seeking a maintained watch may accept a disclosed replacement. The seller's job is to describe the parts and the evidence clearly enough for either buyer to decide.