Watch Glass

The Go-To Guide for Watch Glass

As the window of timepieces, watch glass serves the purpose of defending the dial and hands from impacts and damage.

The question is, which watch glass is best? What are each of these glass types? How do they perform and compare to one another?

Well, here’s a quick guide to each type of watch glass, to help you discern which may suit your needs the best!

Watch Glass Material

- Acrylic Crystal (plexiglass crystal)

Acrylic Crystal (plexiglass crystal)

Sometimes known under the pseudonyms ‘Perspex’ or ‘Plexiglass’, acrylic crystal is essentially a specialized form of plastic (polymethyl methacrylate), that is contoured to fit over a watch dial.

You will often find flat pieces of acrylic crystal fitted to extremely low-cost watches, due to its low retail cost. This type of glass is also often used on retro-inspired watches, as it can be effortlessly manipulated, allowing watchmakers to create domed glass very easily; creating a nice distortion when looked at from an angle. Overall, some people prefer the look of acrylic, whilst others think it looks cheap.

While acrylic glass is very affordable, its softness makes it very susceptible to scratches; though is surprisingly resistant to impacts, due to its flexibility. The pseudonyms previously mentioned are certain variants of acrylic glass with marginally different features, but overall very similar performance.

Pros:

– Shatter resistance

– Can be buffed to remove small scratches

– Inexpensive

– Lightweight

– Vintage appeal

Cons:

– Very easily scratched and marked

– Multiple scratches can impair dial visibility

– Considered by some to look ‘cheap’ (subjective)

– Low transparency and clarity

Mineral Crystal

Overall, the performance of tempered mineral crystal is better than acrylic: harder, better scratch resistance and higher transparency. For these reasons, most mid-range watches are still featuring this crystal. But when compared to sapphire crystal, it performs mediocrely.

Pros:

– Harder than acrylic crystal

– Better scratch resistance than acrylic crystal

– More corrosive resistant than the acrylic crystal

– Higher transparency and clarity

Cons:

– Far less scratch resistant than sapphire

– If damaged (i.e. cracked, heavily scratched or chipped), repairs generally aren’t possible; replacement crystal would be necessary

– Can chip when impacted

K1 Crystal

K1 crystal is heat-treated mineral glass which is more scratch resistant than normal mineral glass and has better shatter resistance than sapphire crystal. In short, K1 crystal is the improved version of mineral glass.

Pros:

– Higher transparency than acrylic crystal

– Better shatter resistance than sapphire crystal

– Its hardness is second only to sapphire crystal

– Higher scratch resistance than regular mineral crystal

Cons:

– Prone to breakage if it falls or hits an object

– Scratches are rare but still possible

Sapphire Crystal

Usually the default choice for higher-end watches, to many Sapphire is the optimal material when it comes to watch glass; primarily because it is the hardest crystal available. You will struggle to scratch a sapphire crystal with anything other than a piece of diamond.

Pros:

– Hardest crystal among all, with a Mohs scale of 9

– The highest level of scratch resistance

– Highest transparency and clarity

– Corrosion resistance

Cons:

– Higher cost

– Prone to shattering upon heavy impacts

– If damaged or smashed, repairs generally aren’t possible; replacement crystal would be necessary

GLASS SHAPE

From the front, the shape of the glass must match the watch case, basically consistent with the shape of the case, here we mainly list the difference from the side view.