The dial out of my 1016 - "OCC" - what is this?

[Spencer PK]

I am a watchsmith, I specialize in vintage models, mostly Seiko. But I also own and work on other things - Omega, Rolex, ETA stuff, Valjoux etc.

A few years ago I inherited my great-uncle's Rolex 1016. Serial is in the late 1966 range. He'd managed to completely flood the watch with pool water, decades ago, and just threw the water-filled watch in a drawer. When it came to me it was a badly corroded wreck.

I did manage to save it, including most of the original movement, but the dial was really badly damaged. Rather than use it, I put in a service dial.

The original dial is a mystery though - is it fully genuine Rolex? Or was it a reprint? Maybe some kind of service dial? It is Singer-marked on the back. It has a minute track, Officially Certified Chronometer text, and was originally a gloss lacquer finish. The minute track and all text, and the marker plots under the lume, are all white and seemingly in or on or on the bottom of the lacquer top coat.

Here are some photos. The last shot shows the original crystal that was on the watch when it came to me.