Omega, "DiVincenzo & Arienti Case", "US market", "Diamond Dial", ca 1964.

The company DiVincenzo & Arienti, based in New York, used to manufacture watch cases for several well-known brands such as Omega, Rolex, Jaeger-LeCoultre/LeCoultre, Longines, and Eglin. During that time, shipping watches without cases was a common practice to avoid the high duty rates on gold.

Interestingly, the watch's connection to the US can be traced through the letters "OXG" found on its movement. This is the import mark for Norman Morris, who were agent for Omega watches in the US during that period.