First off, thank you everyone who commented and helped me on my previous post in identifying this watch! A few days ago I got in contact with a local seller who as downsizing his collection. Most of the watches were fairly inexpensive but he said he had an Omega Constellation from the 1950s. This was the photo I received: The case looked very nice as did the hands and crown. The dial looked a bit worn, which I partially attributed to lighting. Unfortunately the seller did not have photos of the movement and did not want to open it so I took a bit of a risk and came to a deal without seeing the movement (I know, a big no no ). I picked up the watch a few days ago and the dial looks A LOT better in normal lighting. I have attached a few photos in different lighting. The case to me appears unpolished with original hallmark and sharp lines inside the lugs. The caseback is also very crisp with original embossing remaining on the observatory logo: Today I finally had the chance to take it to a watchmaker to have the caseback opened safely. Unfortunately, it is not a 352 RG as I had hoped but a 354 bumper movement. The 13.9 mil serial dates it to 1953/1954. The interesting thing is the caseback. It shows English assay marks and is marked "OWC" but also retains the Swiss Helvetia. Has anyone seen this before? The reference is 2648 as other members previously guessed. As an added bonus, the seller retained the original buckle after all these years, marked "MWF" 9K. This also fits with a British delivery!