Free shipping worldwide on orders over $100


Your Cart is Empty

Sapphire glass watch crystal



Protecting and displaying the face of a wristwatch is a thin clear cover that's typically referred to as the watch crystal. Watch crystals come in a myriad of shapes and sizes to fit the design of all the different timepieces being designed and sold. Crystals also come in varying thicknesses and quality. Watch brands today consider three attributes when selecting a crystal:

Clarity, Durability, Cost

Even with all the variations in size and so forth, watchmakers will use one of three distinct materials for their crystals, listed in order of least to most expensive:

1. Plexiglass (plastic), 1st image from the left

2. Mineral glass, 2nd image from the left

3. Sapphire glass, 3rd image from the left



The least expensive type of watch crystal is a form of plastic, made of the softest material of all three crystals. It is commonly referred to by several names, including Plexiglass, Hesalite, and Acrylic.

Pros of Plexiglass Crystals:

  • Easy to manufacture and manipulate to whatever shape desired
  • Inexpensive to produce; cheap to replace
  • Simple to re-polish
  • It won't shatter or break easily. When it does break, generally it will crack, but stay in place, protecting the wristwatch's dial and movement from further damage.

Cons of Plexiglass Crystals: 

  • It scratches easily
  • Lots of scratches can impact visibility, and then will require the owner's efforts to either re-polish or replace the crystal

How do you know if a particular timepiece, or one you own, has a plexiglass crystal?

  • You might describe a plexiglass crystal as warmer to the touch
  • Provides less vivid viewing, compared to the other two materials
  • Has an abundance of scratches and clouding
  • A better method to determine that it is indeed plexiglass is by tapping it gently with your fingernail, as it will produce a plastic-like tone

For the most part, you'll find plexiglass in vintage pieces. In cheaper watches though, it is also used for various 'tool' watches when an “unbreakable” quality is required.


Slightly more expensive, mineral glass crystals are used generally in wristwatches priced towards the lower end of the market. Almost identical to the glass contained in your windows, additional chemical and heat treatments are used to strengthen and harden the crystal.

The main advantages of using mineral glass crystals are:

  • Decent scratch resistance
  • Fine clarity
  • Relatively low price

Pros of mineral glass crystals:

  • Looks similar to sapphire at a fraction of the cost
  • Not as brittle as sapphire
  • It's much more scratch resistant than plexiglass
  • Can be coated to increase scratch resistance
  • Less expensive replacement crystal when repairing watches

Cons of mineral glass crystals:

  • Scratches easier than sapphire
  • Won't withstand impact as well as plexiglass  
  • Harder to polish than plexiglass

Expect to find mineral glass crystals on a wristwatch geared towards those on a budget. That doesn't make its use an indicator of poor quality overall as many high-quality timepieces use hardened mineral crystals.

How do you tell if a watch has a mineral glass crystal?

  • It will be cooler to the touch, like window glass.
  • They should be clearer than plexiglass.
  • They should have fewer scratches.
  • The fingernail test works well, producing a higher-pitched sound.



The most expensive of the watch crystals, sapphire has gained popularity in recent years, and its use within the industry has exploded. Unlike its natural counterpart, this type of sapphire is synthetically produced in a lab. Aside from a few notable exceptions, high end watches built in the last couple of decades, are almost exclusively equipped with sapphire crystal.

Sapphire Crystal | Sapphire Crystal vs Mineral Crystal

Pros of sapphire crystals:

  • Superior scratch resistance. Only moissanite (9.25) and diamonds (10) exceed its hardness ranking (9) on the Mohs scale
  • Exceptional clarity
  • Use of an Anti-reflective coating makes the crystal seem to disappear

Cons of sapphire crystals:

  • Synthetically made
  • Most expensive option
  • Prone to shattering due to its brittle nature
  • Difficult to polish

How do you tell if a watch has a sapphire glass crystal?

  • Cool to the touch
  • Few, if any scratches
  • Excellent clarity
  • Try and scratch it with a metal object*
  • You also can use professional machine to measure the density, luminousness, refractivity, hardness and some other technical information
  • Color, the colour of sapphire is a little pink or milk white, and mineral glass often have blue color (as reference picture below)

Sapphire crystal glass vs Mineral glass
 If the crystal is mineral glass or plexiglass, you might end up with a crystal repair bill.


AR Coatings:

Sapphire crystal is more reflective than mineral crystal due to its higher index of refraction. (1,8 compared to 1,47). Applying one or more layers of AR (anti-reflective) coating will limit this reflection to a very low level. Very often, lines and marks on the top surface of a sapphire crystal are mistaken for scratches but are actually the scratched AR coating, or just AR coating wearing off after time. An AR coating on the inside of the crystal provides a good AR performance while avoiding this problem. If you do scratch a sapphire crystal, then it cannot be polished away and will need to be replaced.

Sapphire Crystal | L Gasket & Crystal

Waterproof gasket:

As both mineral and sapphire crystals are extremely hard, they have little or no “flex”. This means that when the crystal is inserted into a hard, steel or titanium watch case, it requires a gasket to ensure a waterproof seal.  These crystal gaskets are typically made of nylon, and are either flat, “I”-shaped or “L”-shaped. (see example above). The crystal is pressed into the case, using a crystal press tool. When it is pressed in, the nylon crystal gasket is “squeezed” between the crystal and the case rim, making a reliable waterproof seal. Over time, these crystal gaskets can become brittle and break, so it is a good idea to change the crystal gaskets every few years, to ensure the ongoing waterproof performance of your watch.


All of the options for watch crystals available today provide an incomplete solution, having their individual strengths and weaknesses.

  • Plexiglass is the best at resisting hits and bumps and may even suit certain styles of watches better, though it lacks in clarity and scratch resistance.
  • Mineral glass, with added treatments, can be a worthy and economical substitute to sapphire but comes up short in scratch resistance.
  • It’s the sapphire crystal that demands the highest premium, and for the most part, remains the choice of luxury brands for their watches for its clarity and strength, even with the potential for it to shatter under an impact.

All three materials have applications where their strengths make them the best choice. Even so, sapphire crystals will remain the "crown jewel" of timepieces for a long time to come. You just cannot beat sapphire when scratch resistance and clarity are demanded. In this case, Aiverc decided to use sapphire glasses with Anti Reflection Coating. 

  • 316L stainless steel

    Sapphire glass with AR coated

    PVD plated

    Japanese miyota movement 2035

    Quick release straps

    Premium genuine leather

    3D pressured dial

    50 meter water resistance

    2 year warranty