Over the years, Omega has produced hundreds of offshoot watches, but for purity's sake (and brevity's, for that matter), we will focus on the purest of all Speedmasters here.
Further, this is not a look at The very first thing that one must understand about the Speedmaster is that in 1957 when it was launched, chronographs made up a very, very small percentage of watch sales – for all brands.
I've also seen them with black bezels and alpha hands (what you'll find on the next watch, reference 2998).
I've seen 2915-3's with a steel bezel and alpha hands; I've seen them with a black bezel and broad arrow hands.
The 2915-3 is a remarkably complicated watch to authenticate and value because of all this, whereas the 2915--2 sit more clearly in the upper echelons of watch collecting, thanks to the relative lack of ambiguity in identifying them and establishing that they're correct.
As I mentioned above, the 2915 is certainly the earliest of the Speedmaster series, but I would argue the 2998 is potentially more important, and even the archetype for what we know today.
Consider this original advertisement for the 1957 Omega Speedmaster seen below.
So it could look like a 2998, but at the same time, it may look I have seen 2915-3's with steel bezels and broad arrow hands.Heuer would make up for this in the 1970s with the introduction of the early Speedmasters and just plain early Speedmasters, the 2915 is actually a dramatically different watch when you begin to examine the little things.The dial, for example, should feature an "Omega" with an oval shaped "O." The tail of the "R" in "Speedmaster" should also be quite long on early watches.This is part of the reason why sports-oriented chronographs from any maker – including Omega – are so much more coveted than their simpler counterparts.Not only are they more complicated, but they are also far more rare, with a target market much narrower than their simple time-telling brothers.The thing is, all of them could very well be correct.