There are various types of crystals that are used in the watches we love to wear on our wrists. The types of crystals vary mainly in how prone the glass is to scratching, but they serve the purpose of protecting the dial of the watch from being scratched.

As mentioned, the crystals vary based on the toughness, and can be rated on the Moh Hardness Scale. The higher the score on the scale, the more scratch resistant it is.

The first type of common crystal is the acrylic crystal. This type of crystal normally comes in at a 3 or 4 on the Moh Hardness Scale. Acrylic is really a plastic that has the appearance of glass and is tough yet flexible and light. Acrylic crystals are known for being more prone to scratching. This can be annoying to some collectors, but to others, it allows the watch to carry some really cool marks from some pretty amazing stories. Being lower on the Moh scale, many scratches that occur on an acrylic crystal can be polished out.

The next time of crystal is the mineral glass crystal. These are treated with heat and chemicals to be scratch resistant. You do not find these on many watches, but they are often found on watches from the ‘fashion’ watch category.

The last type of crystal is the sapphire crystal. These crystals come in at a 9 or 10 on the Hardness Scale and are widely used in modern watches. The sapphire is synthetic and because of its hardness score, are the least prone to scratches, chips or shattering.

If we look at vintage watches, typically acrylic crystals are found in watches before the 1980’s. If we look at Rolex, acrylic crystals were used in watches until 1970 when Rolex released their first quartz watch, the reference 5100. This watch was fitted with a sapphire crystal, but acrylic crystals were used up until the 1990’s.

Enjoy!