I think it is most likely white gold. Please see my thread below (another piece I obtained from the 70s with the same dial). When I am next in NYC I will stop by the boutique and likely order an abstract. www.watchprosite.com Enjoy yours!
It is a great time piece with a very useful complication. If you want something more simple go with the standard 3-hander. Some people feel the am/pm indicator is a bit "quirky" but IMO it's great. I have red, white and blue rubber straps. It looks great on the rubber strap as well as the bracelet.