I should be more clear -- I am talking about the specific Speedmaster reference that NASA chose to be its official watch.
I believe the First Omega In Space (FOIS) was the 2998 but this was privately owned by Mercury Astronaut Wally Schirra. NASA then tested the 105.003 and this was approved and issued to Astronauts beginning with Gemini 3. Later flights also used the 105.012 and 145.012
and 105.012-66CB on the wrist of Cernan was the last watch on the moon, convenient as its the only sub-reference that wears its ID card on its lugs.