Sapphire glass watch | mineral glass | watch glass | test | comparison | scratch | polish

Sapphire glass

Sapphire crystal is exceptional. Below I explain the best 3 properties and also give a brief insight into the production.

TOP 3 best features of sapphire crystal

1. Scoring hardness
2. Colorlessness
3. Traction

1. scratch hardness

Is sapphire crystal scratch resistant? Yes!
With a scratch hardness of 9 on the Mohs scale of the German-Austrian mineralogist Friedrich Mohs, sapphire crystal is close to the optimum hardness level that can be achieved with currently known materials. Only diamond with a reference value of 10 is even harder and immediately represents the upper end of the scale.
This is one of the reasons why many watch connoisseurs nowadays swear by a sapphire crystal watch. Although, strictly speaking, it is made neither of a real sapphire nor of glass. Sapphire glass, which came on the market in the early 1980s, is obtained in its raw form from artificially produced corundum, which is relatively costly to manufacture because several melting steps must be applied at different degrees at different rates to obtain the perfect „sapphire glass.“

You are probably wondering why sapphire crystal is called sapphire crystal and not „corundum crystal“. This question can be answered by the fact that a sapphire is a specific variety of corundum, and the name sapphire is much more commonly used than corundum in the general public.

2. colorlessness

Unlike real sapphires, which have a slightly bluish appearance, an artificially produced sapphire is colorless and therefore ideally suited as a watch crystal.

3. traction

The traction of sapphire crystal is above that of the eternal competitor „mineral glass“.
Despite the very good properties of sapphire crystal, it is not indestructible. You should not drop your sapphire crystal wristwatch too often. If the angle is unfavorable, the glass may break because the maximum tensile load cannot withstand the maximum compressive load. The tensile load of sapphire crystal reaches about 1/10 of the maximum compressive load.

In concrete terms, this means that when pressure is applied to the glass from the front, the back is also always subjected to tension. If the tensile load is exceeded, the glass may break. However, this nominal weakness of sapphire crystal also exists in the competitor „mineral crystal“, as already mentioned above.

Single-sided or double-sided anti-reflective sapphire crystal – Which is better?

Important to know, sapphire crystal in its original form refracts light very strongly, so you should definitely make sure that the sapphire crystal is anti-reflective on one or both sides when buying a watch. Whether single-sided or double-sided is a matter of taste. The advantage of sapphire crystal with anti-reflective coating on one side is that the watch retains its scratch resistance. On the other hand, sapphire crystal with anti-reflective coating on both sides has the advantage of better readability. The scratch resistance decreases superficially, but you can also grind off the extra anti-reflective layer on the glass and say adiós to the scratch. In the chapter „What to do if the watch is scratched? Polishing sapphire crystal properly -care instructions„you can learn more about it.

Acrylic glass (plexiglass, acrylic glass, hesalite glass)

Acrylic glass, which is also known as Hesalite glass or Plexiglas (both are once trademarked names for this type of glass by watch companies), is once again less expensive to produce than mineral glass. However, it cannot hold a candle to other types of glass in terms of scratch resistance and is therefore rarely used in watches.
One watch brand that partially relies on this glass in their watches is, for example, the German watch manufacturer „Junkers“. (under the name of Hesalite glass)

The advantage or disadvantage, depending on your preference, of acrylic is that it is very light and minor scratches can be polished out relatively easily. The disadvantage of this glass is that it is easily scratched because the scratch resistance is only 500 Vickers.

Gorilla glass as watch glass

Gorilla Glass mainly comes from smartphones. In fact, it does not belong to the classic watch glasses. Recently, however, it has also been used in many smartwatches. It is currently mainly used in smartwatches and fitness watches. Gorilla Glass is made of alkali metal silicate and has improved durability due to an ion exchange process. This creates a certain surface compressive stress and protects the glass from scratches. In addition, the break resistance of Gorilla Glass is 8 times higher than that of conventional (mineral) glass.

Gorilla Glass vs Sapphire Glass Watches

Currently, the hardness and scratch resistance of gorilla glass can not compete with sapphire glass. However, it is constantly being developed further and it can be assumed that gorilla glass will replace sapphire glass in an improved form one day in the next few years. But there is still a long way to go until then.

Comparison Table Sapphire Glass vs Mineral Glass vs Gorilla Glass vs Mineral Glass with Sapphire Coating

How can I recognize a sapphire crystal watch?

It is very difficult to tell with the naked eye which glass has been used in a particular wristwatch. If one touches or taps the glass, however, it can be guessed from circumstantial evidence. For example, sapphire crystal is usually slightly colder than mineral crystal at the same room temperature.

Sapphire crystal water test – drop remains compact on right MNMA Series 1 watch compared to mineral crystal watch where drop „smears“

Tapping the watch glass also provides further clues about the installed watch glass; it feels dull with sapphire glass and rather bright with mineral glass.

Another test is to apply a drop of water to the center of the glass of the watch in question. If the drop retains its shape, there is a high probability that sapphire crystal was used. If the drop loses its shape and runs, you can be relatively sure that the wristwatch has mineral glass. See also the picture on the right, we once compared a MNMA Series 1 with real sapphire glass with a watch from another manufacturer, which „only“ has mineral glass as installed glass – we find in the comparison, the difference is clearly visible.

It gets a bit more difficult when a special coating has been applied to the upper side of the glass, for example for better readability. Due to the coating, the drop may run despite the installed sapphire crystal, so we recommend the diamond tester method.

The last and safest method is provided by the
Diamond tester*
which is normally used to test gemstones for authenticity. However, it also works for watch glasses. The diamond tester tests the thermal conductivity of the glass. Sapphire glass differs in this respect, as it conducts heat very well, much more than any mineral glass.

To do this, the first step is to heat the tip of the device to a certain number of degrees. The front end of the device is then pressed onto the watch glass, after which the speed at which the tip cools down is measured. The various luminous points on the device show how strong the cooling is on contact and provide information about the thermal conductivity of the respective watch glass. Reliable can be purchased in specialized stores for a small amount.

Now let’s look at what you can do if there are scratches on the watch.

Polishing sapphire crystal correctly – care instructions

A watch is a piece of jewelry and usually not a cheap accessory. Pieces of jewelry need to be taken care of, so that even after some time you do not lose any of its luster.

Proper care for sapphire crystal is an important aspect and should not be neglected. Therefore, despite the degree of hardness, avoid corresponding shocks or friction on your watch. If you still see irregularities on the glass, they are usually other substances disguised as „scratches“. You have the possibility to easily remove these potential „scratches“ by buying a commercial eraser.

However, if real scratches do get on the watch, it is difficult – but not impossible – to polish the scratches out again. For the craft professionals among us, it is an advantage to have a
Dremel*
tool is available in the household. Buy in addition Diamond grinding paste* with a 3000 grain and
Polishing felt*
, of course everything at your own risk. If you are appropriately careful and have some time and patience, the sapphire crystal will soon look like new. However, if you do not have any knowledge in this area, it is advisable to go to the craftsman you trust or have the glass replaced by the jeweler.

Important: Some manufacturers install sapphire crystal with an outer anti-reflective layer on the sapphire crystal. This AR layer serves for a better anti-reflection coating. However, this leads one of the main advantages of sapphire crystal ad absurdum, the scratch resistance is lost.

Before buying, you should find out whether your watch has an outer AR layer and whether you would like to keep it if you plan to polish it, since it will be ground off by the diamond grinding paste.

Say goodbye to scratches and get your sapphire crystal watch from MNMA now!

Scratch-resistant, shatterproof & minimalist – from 139 euros ☑

We put an end to annoying scratches on the watch. We install genuine sapphire crystal in our wristwatches for maximum durability.
In addition, each of our watches has at least 5 ATM water resistance, so you can wear it even when showering, for example. The Sony battery inside increases the runtime by up to 12 months compared to a conventional battery. The installed very power-saving Swiss or Japanese quality movements from Ronda or Miyota guarantees the highest precision with perfect runtime. Write to us if you have any questions about us or our watches.

We put all our expertise into the Series 1 to create you a durable watch series at a great price with very good components.

Preis	169 Euro	159 Euro	139 Euro	149 Euro
Modell	CLASSIC CLEAN	MNMA MILA SUPERSTAR	MNMA BISCUIT	GOOD TIMES EDITION
Uhrenglas	Echtes Saphirglas doppelseitig entspiegelt	Echtes Saphirglas	Echtes Saphirglas	Echtes Saphirglas
Uhrwerk	Chronographen Uhrwerk von Miyota	Schweizer Uhrwerk von Ronda	Schweizer Uhrwerk von Ronda	Schweizer Uhrwerk von Ronda
Gehäusebreite	45 mm	42 mm	42 mm	42 mm
max Gehäusehöhe	12 mm	7,6 mm	7,6 mm	7,6 mm
Armband	Lederband in Schwarz	Milanaise Band in Schwarz	Lederband in Senfgelb	Lederband in Haselnussbraun
Zeiger	Stoppuhrfunktion	Fluoreszierend	Fluoreszierend	Fluoreszierend
Wasserdichte	10 ATM	5 ATM	5 ATM	5 ATM

3. PAUL HEWITT – Black sunray PH-C-BSR-2m

The Paul Hewitt brand originates from Oldenburg and has developed from a small startup to a global player by means of e-commerce since its founding year in 2009. The offer includes not only watches, but also jewelry such as bracelets, cell phone chains, necklaces, earrings and rings, with the typical anchor serving as a style-defining element. The watch models combine chic minimalism with a touch of elegance. The model ,,Black Sunray
PH-C-B-SR-2M*
“ from the Chrono Line focuses on a dark accent, as it consists of a black leather strap, black dial and black stainless steel case.

Weiterlesen...

Conclusion:
The PH-C-B-BSR-2M* is arobust, well rated sapphire crystal watch without major weaknesses that scores with its water resistance and of course the genuine sapphire crystal at a price of approxPrice not available*. Besides the leather strap, the watch is also available with e.g. Mesh strap available.

What we like:

☑ Sapphire crystal
☑ Calendar function
☑ 5 ATM water resistance
☑ Renowned brand movement from RONDA, SEIKO, EPSON or MIYOTA
☑ Stopwatch function

Where do we still see potential:

– Second hand almost as big as minute hand, relatively difficult to read
– narrow hands

2. fossil mens chronograph quartz watch fs5384

BERING is a Danish jewelry and watch manufacturer, which has purism, excellent workmanship as well as a long life of the watches engraved on its banner. The model ,,Classic – 14240-303* “ also comes in slim design and is equipped with a blue Milaniase bracelet.

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Conclusion:
With the Classic – 14240-303* Bering has a hot iron with an icy touch in the fire. We especially like the solid color scheme of the watch and the details that are subtle but placed in the right places. The price for the watch is about
134,25 EUR*
incl. VAT

What we like:

☑ Slim design
☑ Handling
☑ Sapphire crystal

Where do we still see potential:

– 3 ATM
– Unspecified quartz movement
– price

1. casio wave ceptor mens wrist watch

The watch pioneer
Casio*
with the legendary Wave Ceptor* , is of course also represented in our list. The very popular model comes in silver with a black dial and has an integrated solar function as a special treat.

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Conclusion:
A real watch for real men. Casio lives up to its reputation as a global BigPlayer and gives the
Wave Ceptor*
many good components for the price of approx. 199,20 EUR*. Besides the good components, we also like the available solar function, of course.

What we like:

Hybrid analog digital display
☑ Solar function
☑ 5 ATM water resistance
☑ Sapphire crystal

Where do we still see potential:

– unspecified movement
– price

Insider Tip:
MNMA Chronographs Sheriff Series

Brand: MNMA

The MNMA SHERIFF is the latest model of the company from Germany and combines chronograph look with reduced design. All this is combined with a classy mesh strap and the full range of high-quality components, such as 10 bar water resistance and sapphire crystal.

Weiterlesen...

Conclusion:
A chronograph model as a noble black edition with minimalist design and high quality components at a price point of
229 Euro
. If you want to enjoy your purchase for a long time, you definitely won’t go wrong here and will enjoy your wrist companion. Optionally, the model is also available with individual engraving.

What we like:

☑ Japanese chronograph movement Miyota
☑ Doppelt entspiegeltes Saphirglas
☑ Water resistance of 10 ATM
☑ Case size 45mm
☑ Minimalist design

Where do we see potential:

➖ Brand still relatively unknown

Conclusion – Which watch glass is the best?

Buyers who value maximum durability, scratch resistance and the look & feel of a wristwatch will be happy with a sapphire crystal watch. Nevertheless, wristwatches with mineral glass as well as sapphire glass have their raison d’être.

If price is the main consideration for a wristwatch, mineral glass is a sensible choice to keep the overall price down, as manufacturing is at a cheaper level.

You should not necessarily bet on a watch with acrylic glass, unless the purchase price is less than 40 euros.

With the other properties of mineral glass, the price-conscious buyer definitely gets a solid glass base for his wristwatch, but in case of doubt, he has to reckon with a new purchase rather than if a higher-quality glass is installed.

The mixed combinations of the two glasses are not recommended nowadays, in our opinion, because the production is expensive and the production costs of sapphire glass have decreased. Which largely offsets the former advantages.