Was the Oysterquartz the first Rolex to have a sapphire crystal?
No. The Rolex Quartz Date Ref 5100, which was the forerunner to the Oysterquartz, came with a sapphire crystal. The aforementioned 1530 Perpetual Date and 1630 Perpetual Datejust models also came with sapphire crystals. The Oysterquartz was actually the third Rolex model to come with a sapphire crystal.
