What makes watches water resistant?

1. Gaskets: The most critical component in making a watch water-resistant is the use of gaskets. These are small rubber or silicone rings that are placed between the different parts of the watch case, such as the crystal, the caseback, and the crown. Gaskets create a watertight seal that prevents water from entering the watch.

2. Screw-down crown: A screw-down crown is a type of crown that is screwed into the watch case. This creates a more secure seal than a regular crown, which can be easily pulled out.

3. Sapphire crystal: Sapphire crystal is a type of watch crystal that is made from a synthetic material called corundum. Corundum is extremely hard and scratch-resistant, and it also has a high melting point. This makes sapphire crystal an ideal material for watch crystals because it is resistant to both water and scratches.

4. Pressure-tested: In order to ensure that a watch is water-resistant, it must be pressure-tested. This involves submerging the watch in water and applying pressure to it. The watch is considered water-resistant if it does not leak under pressure.

5. Water-resistance rating: The water-resistance rating of a watch indicates the depth at which it can be safely submerged in water. The most common water-resistance ratings are 30 meters (3 ATM), 50 meters (5 ATM), 100 meters (10 ATM), and 200 meters (20 ATM).

It's important to note that water resistance is not permanent and can be affected by factors such as wear and tear, aging, and improper use. It's always a good idea to have your watch checked regularly by a professional watchmaker to ensure that it maintains its water resistance.