New Arrival, Job Number 190106

At one time plastic watch crystals were considered an upgrade over glass as they were "unbreakable". Most people assume they are not original, but in fact they often are. Plastic used for watch crystals goes back much further than one might think. There were quite early formulations of acetate and acrylic materials common as early as the 19-teens. The problem with these early materials is that they decay over time becoming yellow, blue or green. And while doing that, a corrosive gas is released.

I see many watches like this one that internally, to look in the back, look great. Nothing is broken and there's no sign of rust, damage or excessive wear. But the hands are gone. The rust is too sever to save them, due to the crystal. Unfortunately, I often find in these cases that the cannon pinion and other parts near the center front of the movement are likely also damaged.

There are mixed opinions as to whether a discolored crystal should be left on the watch as original, or replaced with glass. There are mixed opinions as to whether to degassing continues decades after the discoloration has occurred (any chemists out there?). But most people want a glass crystal put on. Glass crystals are extinct in some sizes and types now, but usually there is a plexiglass substitute which is stable and almost indistinguishable from glass.