October 28 2017
Sapphire crystals are typically found on newer watches (for Rolex, post-c.1987) and feature greater scratch resistance than plastic/acrylic crystals. These can be identified because they are typically flatter and more flush with the case than the more bulbous or curved plastic crystals. Additionally, some people can tell the difference by feel: a sapphire or glass crystal will be cold to the touch, whereas a plastic/acrylic crystal is typically closer to room temperature. Though more scratch resistant, there are several drawbacks to sapphire crystals: 1) When a sapphire crystal is scratched, the scratch cannot be buffed out, and the crystal must be replaced. 2) If dropped, a sapphire crystal is more prone to shattering than a plastic crystal, which will more typically just crack. If a crystal shatters, shards can scratch a dial, or potentially enter a movement and cause havoc in the gears.
The vast majority of wristwatches produced before the 1990’s will have a plastic or acrylic crystal, although some will have glass, which is similar to sapphire, though without its scratch resistant properties. In any case, some people prefer the vintage aesthetics of a more curved, plastic crystal, to the more flat sapphire material.
How do I remove scratches from plastic/acrylic crystals?
Unlike a sapphire crystal, a plastic/acrylic crystal can be polished many times before it needs to be replaced.