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How sapphire glass is made. Basic properties of sapphire glass. Mineral glass for watches

Today, two equal options are used to protect the screens of modern popular communications equipment - artificial sapphire or chemically modified Gorilla Glass. Each of the solutions has a number of advantages and disadvantages, so it is impossible to objectively call one of them more interesting with all the desire. In this article, we conduct a full comparative analysis of these materials - from the moment of production to the possibility of replacement.

So which is the best screen protector - sapphire or Gorilla Glass?

Sapphire and Gorilla Glass - introductory

What is sapphire crystal

Sapphire is a superhard form of transparent crystal. Outwardly, it resembles glass, but in terms of its physicochemical properties, it is much closer to diamond.

Interesting fact
Artificial sapphires were first synthesized in 1904 by the French chemist Auguste Verneuil.

Today, this material is used to create various medical devices, as well as to protect the dials of expensive watches and the screens of some modern luxury phones, most of which have the Vertu logo on their cases.

What is Gorilla Glass

Gorilla Glass is a glass that has increased resistance to scratches, bending and shock. This is achieved by chemical treatment, namely, ion exchange, during which the corresponding sodium elements in the material are replaced by potassium particles.

Interesting fact
Project Muscle - the forefather of Gorilla Glass - was closed in 1959 and revived at the personal request of Steve Jobs only in 2006.

Today, Gorilla Glass is overwhelmingly used to protect the screens of modern mobile phones, but it is also beginning to be used in the production of notebooks with touch screens, as well as in the automotive industry and even construction.

Comparison of the hardness of sapphire and Gorilla Glass

Sapphire is a considerably harder material than any material available for use in phones.

Note
Mohs scale (mineralogical scale of hardness) - a set of ten reference minerals - from talc to diamond - for determining the relative hardness by scratching.

The hardest is a diamond - 10 points. The hardness of the sapphire is estimated at 9 points chemically modified glass Gorilla Glass - 6.8 points... For comparison, the hardness of gold - 2.5 points, steel - 4 points, ordinary glass - 5 points, grade 5 titanium - 7 points, forged steel - 7 points. The harder material scratches the soft material without any problems - sapphire can only be scratched with a diamond, Gorilla Glass - even with a simple keychain.


Is it really impossible to scratch a sapphire with anything but a diamond?- we also want to answer this question. Vertu had a problem with scratches on the screen, and many users doubted that it really was a sapphire, because everyone is convinced that there is nothing in the everyday life of an ordinary person that could damage it. Scratches appeared - if we are talking about women with Vertu - from diamond earrings that came into contact with the display at the time of the conversation - they have a greater hardness than sapphire

Our own visual test comparing the hardness of sapphire and Gorilla Glass

The numbers are, of course, great, but we decided to conduct an independent test for the resistance of the sapphire to scratches. We just had a sapphire crystal from Vertu Ascent lying around, so, as they say, God himself commanded.



For the experiment, we used the most ordinary P400 sandpaper purchased from a car dealership. We rubbed the test piece with it well. It took a lot of effort to achieve the visible effect, but still we managed to scratch the sapphire.

How and why did it happen? The thing is that the sandpaper contains corundum, it, like sapphire, has a hardness of 9.



To enhance the effect of the impact several times, we used a bur-machine with an abrasive nozzle. But, apparently, the composition of the abrasive contained less hard particles than corundum and sapphire, in general, could not be scratched at all, the nozzle simply glided over the surface, we will not leave a trace. Perfect result. Sapphire is really hard.



We continued our practical test by replacing the sapphire with GorillaGlass. Fortunately, we have at hand the original glass from the iPhone 6 after repair. For the purity of the experiment, we used exactly the same sandpaper as in the case of the previous subject. The result turned out to be very predictable - it was not difficult to scratch the material.



Replacing the sanding paper with a boring machine turned out to be even more impressive - the nozzle went like a knife into the oil, depressions visible to the naked eye formed on the glass. There is no doubt that sapphire has resisted such actions with great dignity.

Sapphire and Gorilla Glass pros and cons

Each has its own pros and cons.

Specifications Sapphire Gorilla Glass
Hardness Sapphire is much harder than any other screen protector, making it very difficult to scratch. However, as our personal tests show, nothing is impossible. Gorilla Glass is less durable than sapphire. This material can be scratched even with metal objects such as keys.
Flexibility Sapphire is very inferior in terms of flexibility, so if you press on the device, it can crack without any problems. Gorilla Glass is a very flexible material, so pressure on the screen of the device by any foreign objects cannot critically damage it.
Strength The strength of sapphire is poor - it is very fragile and can be easily damaged upon impact. That is why, by the way, the sapphire crystal in Vertu phones has an impressive thickness, which partially eliminates this shortcoming. Considering the much higher strength index compared to sapphire, it is much more difficult to damage Gorilla Glass when dropped.
Transparency The clarity of a well-polished sapphire is a benchmark. This guarantees an unprecedented level of image brightness and contrast. In terms of transparency, Gorilla Glass is clearly inferior to sapphire - this can be seen with the naked eye.
Price Sapphire is ten times more expensive than Gorilla Glass, which will definitely have to look out for when repairing. You can replace the screen covered with Gorilla Glass with much less money - this is an absolute plus of the material.

Gorilla Glass is much more bending-resistant than sapphire. That is why pressure on him is unlikely to be able to inflict significant damage on him - he will be scratched, but definitely not cracked. Sapphire, on the other hand, is more likely to crack than scratch. Nevertheless, on Vertu devices, for example, rather thick transparent sapphire plates are installed, so this drawback is partially leveled.



Well-polished artificial sapphire is much more transparent than any glass, including Gorilla Glass. This makes the image on the screen of a modern mobile device much brighter and clearer, which greatly improves the perception of any information from it. Considering the fact that it is used both for inputting information and for outputting it, this is an important factor for using sapphire to protect phone screens.



Despite the fact that sapphire, having enormous hardness, resists scratches much better than any glass and retains its original appearance for a very long time, it has an unobvious drawback. This material is very fragile, so it will not be difficult to break it when the device falls. According to this parameter, Gorilla Glass surpasses it a couple of times. That is why massive "solid" Vertu phones, for example, use thick sapphire plates that would be inapplicable, for example, for the same iPhones.



Even taking into account the numerous attempts to reduce the cost of artificial sapphire, which are resorted to by companies around the world, its price currently exceeds that of Gorilla Glass by ten times. In the first case - about $ 30 per sheet, in the second - only $ 3. It should be borne in mind that in this case the cost is indicated not for the finished component, but only for the blank, therefore, sapphire is definitely not suitable for the mass market today.

Popular means of communication with sapphire and Gorilla Glass on the screen



Today sapphire is used to protect screens, with very rare exceptions, only in luxury communications - this is primarily due to the high cost of its production. Moreover, since the technology of growing artificial sapphire of large size is very complex and not widespread everywhere, such material can be found mainly on Vertu phones - both on smartphones like Aster and Signature Touch, and on classic “dialers” like Signature S ...



GorillaGlass is used today in all popular communication media - iPhone, Samsung Galaxy family, LG, HTC phones and so on. Now the relatively low cost of the material allows it to be used almost everywhere. Moreover, with each generation of GorillaGlass (the last for today is its fourth reincarnation), which becomes more resistant to any damage with decreasing thickness, its price only decreases.

Possibility and cost of replacing the sapphire screen and Gorilla Glass



Depending on the option to replace the glass and screen separately, the cost of repairing a damaged Vertu display varies greatly. So, for example, in the classic push-button telephone Signature S this is real, so the price of a sapphire crystal is at the level of 15,000 rubles. In modern smartphones of the company, they are glued together to reduce the air gap and improve the image quality, so in the same Constellation V, for example, if the screen is damaged, you will have to part with the amount of 60,000 rubles.



In the overwhelming majority of cases, the screens of modern mobile phones are glued to GorillaGlass, which makes it possible to reduce the overall thickness of their displays and improve image quality by removing an air gap. That is why, if the glass is damaged, it is necessary to replace it together with the display. The cost of such a procedure in modern iPhone models is at the level of 10,000 rubles, which is significantly lower than similar operations with sapphire.

Manufacturing process of artificial sapphire and Gorilla Glass



To grow sapphire that would fit on mobile phone screens, Vertu created a new technology that is a trade secret of the company. However, it is known for certain that the basis for the process is the use of high temperature and pressure on the alumina. After creating a sapphire "sausage", it is cut into separate pieces of the required size and polished for a long time to full transparency. In the processing of sapphire, diamond tools are used - only such a material can succumb to it.



To give ordinary glass increased hardness and strength, the specialists of Corning will use chemical methods of processing it - the ion exchange process. To do this, ordinary glass is placed in a solution of molten potassium salts with a temperature of about 400 degrees Celsius. During the procedure, small sodium ions in the glass are replaced by larger potassium ions. After the glass has cooled, the potassium ions begin to press against each other more strongly, in comparison with sodium, giving the new material - the very same GorillaGlass - increased resistance to damage.

The near future of screen protectors


If we analyze the current developments and plans of manufacturers of protective glass for phone screens, we can distinguish three directions for the development of these components. The first is based on reducing the cost of sapphire glasses and their mass distribution, the second - on increasing the hardness of Gorilla Glass and similar solutions in a physicochemical manner, the third - on the combined use of glass and sapphire. In the latter case, a thin layer of scratch-resistant sapphire can be applied to the impact-resistant glass - a kind of sputtering.

If you are faced with a choice of good watches, including

sports, you probably noticed that, among other characteristics, the manufacturer almost always indicates the material from which the glass is made that protects the display.

Why is it so important and what kind of glass are there?

The characteristics of glass directly depend on what it is made of. Allocate three main types of material:

1. Plastic glass or organic glass. This option is the most budgetary and is used, as a rule, in inexpensive watch models.

This glass has a number of advantages:

  • It easily bends to fit any watch shape
  • Weighs little
  • It's hard to break
  • Low price.

However, this material is far from ideal, primarily because it is very easy to scratch. It is not necessary to scrape at the clock with a knife - organic glass can become cloudy and “rubbed off” even from ordinary (but regular) contact with clothes. It is really difficult to break it due to its fibrous structure, but it is quite susceptible to mechanical damage, bends easily and does not withstand high pressure.

2. Mineral glass. It also has two names: "Artificial crystal" or "Silicate glass". Such glass has average characteristics in all respects - price, weight, wear resistance and strength. It is much harder to scratch than plastic, but easier to break. Mineral glass is the most popular choice among watchmakers.

Gorilla Glass also belongs to mineral glass - a fairly well-known material that is used in the Iphone, as well as in the watches of some brands. Such glass is quite durable, however, as any Iphone user will confirm to you, it is easy to break and get a "cobweb" of cracks all over the screen. Since the screen area of ​​the watch is much smaller than the screen of a smartphone, it is very difficult to break it - for many years of working with a sports watch, we do not remember even a couple of such cases.

Mineral glass is used in many Suunto models, for example in the Ambit range (except for watches marked with the Sapphire mark, more on that below).

3. And finally sapphire crystal... Another name for this material is monocrystalline aluminum. They are not the same Sapphires used in jewelry are specially grown crystals of aluminum oxide. Such material is more expensive in production, in processing, but at the same time it can only be scratched with a harder material (and there are very, very few of them), for example, diamond. Sapphire is one of the most difficult minerals known to man. It is harder than steel, but more fragile than diamond. Chemically hardened glass may be an excellent material, but sapphire is superior in terms of hardness, strength and durability. Sapphire is 4 times more resistant than the Gorilla Glass mentioned above. On the Mohs hardness scale, used to measure the hardness of minerals, sapphire scores 9 out of 10.

By the way, Apple phones have one element made of sapphire glass - it is it that protects the smartphone's camera.

It is the sapphire crystal that is used in the most expensive watches. Even if your grandchildren will inherit your sapphire crystal watches, they are unlikely to see even one scratch.

Since the production and processing of sapphire glass is laborious and expensive, the price is appropriate. So keep in mind that a similar watch model, but hidden behind a sapphire, will cost significantly more. Suunto uses sapphire crystal in the most premium watches, for example new in 2016

There are also intermediate, combined options - for example, sapphire-coated mineral glass... This technology improves scratch resistance without significantly increasing the cost.

What should you choose? If you want a watch “for centuries” and plan to actively and for a long time use it - choose sapphire crystal! Whatever one may say, this is the most prestigious and highest quality option for most types of watches, undoubtedly adding points to their owner.

Looking for a durable option but want to save some money? Choose watches with mineral glass!

Do you want a large collection of bright plastic watches, buy a simple sports watch with a stopwatch and cut-off, or are looking for the first watch for a child? Choose plastic!

For those who value reliability, durability, durability and visual appeal in a wristwatch, an important parameter is the appearance and quality of the glass on the dial. The correct operation of the entire mechanism depends on the integrity of the glass cover. It protects internal parts from shock, dust or water ingress. As stylish as the design is, chips and scratches on the dial will give the watch a worn and worn look.

Plastic or plexiglass. These materials are by far the most accessible and cheapest of the variety on the market today. The frequency of use is due to its low specific gravity, good plastic properties and ease of secondary processing. The downside is susceptibility to scratches, abrasions, and other mechanical damage. The use of plastic or plexiglass is appropriate for sports models. Replica Hublot watches equipped with plexiglass are very lightweight and withstand dynamic load well. They are practically not felt on the hand and do not interfere with sports or active recreation.

Sapphire-coated mineral glass. This is a material consisting of two layers - the upper one is made of synthetic sapphires, the lower one is made of mineral glass. It has a lower cost than pure sapphire glass, but retains all its useful properties.

Anti-reflective glass. This is a specially treated mineral or sapphire crystal. Most often it is used in the production of expensive watches, glasses, and other goods where anti-reflective properties are important. The presence of glass with an anti-reflective function in the watch will make it possible to distinguish between the dial and hands even in very bright light, for example, under the midday sun. This function is very important if a person spends most of his time on the street.

Mineral glass. This is an intermediate glass option in terms of price, availability and quality. All significant parameters (transparency, strength, density, wear resistance) are at an average level. It has an advantage in watch models where the shades of the hands and the dial are almost the same - the mineral glass allows you to distinguish between the time indicators in the best way. Making a copy of Swiss watches, manufacturers most often use mineral glass because of its practicality and democratic cost.

Sapphire crystal. The scientific name is monocrystalline aluminum. This material is made from so-called synthetic sapphires. Its distinctive features are glossy sheen and very high wear resistance. Most importantly, modern sapphire glass does not become scratched, does not tarnish or grow cloudy during a long period of the most intensive use. However, it is quite fragile, which increases the risk of breaking it if accidentally hit. Almost the only material that can leave scratches is diamond. Therefore, you should not store your watch next to diamond-encrusted rings. Equipped with a sapphire crystal, replica Patek Philippe watches will retain their prestigious and respectable appearance for a long time. Accordingly, the cost of a wrist watch with a sapphire crystal is relatively higher.

Touch glass. Belongs to completely new innovative materials. It is made on the basis of sapphire glass by equipping its inner side with transparent sensitive electrodes that react to heat. Used in new generation wristwatches. Allows you to easily activate additional functions by touching specific points on the glass.

Let's make a reservation right away, we will talk about branded status wristwatches for which plastic is “out of order”. Not because the material is cheap and doesn't emphasize well-being. It just quickly loses its transparency and integrity. The task of the glass is not only to provide excellent visibility of the dial, but also to protect the movement. Considering that in many watch models the mechanics are ultra-precise, sometimes hand-made, it is a matter of honor for the master to ensure its safety. Therefore, in the manufacture of branded watches, mineral or sapphire glasses are used. What is the difference? Let's figure it out.

Mineral glass

75% of wristwatches are protected by such glasses. They perfectly prevent the ingress of dust and moisture into the case, not allowing to "kill" the mechanism. They have the following properties:

  • durable. It is difficult to break them with a direct blow;
  • wear-resistant. In the process of wearing, scratches rarely appear;
  • durability. Service life with proper care is more than 20 years;
  • the possibility of polishing and easy maintenance.

At a low cost, these qualities make watches with mineral glass especially popular. Small disadvantages should be noted: after long-term operation, it becomes cloudy and needs to be replaced.

Sapphire crystal

The protection of the dial and movement, made of artificial sapphire, is highly wear-resistant. To scratch the glass, you will need, at least, to buy a diamond; it is almost impossible to damage the sapphire surface with other minerals. In addition, a watch with such glass will last almost indefinitely for a caring owner. The case, bracelet may wear out, and the glass will remain transparent and intact.

The downside is the fragility of the material. Due to the high hardness of artificial sapphire, the glass may not withstand a strong impact and will simply shatter.

How to make a choice?

To know exactly where the "dog is buried", let's compare both versions of glasses in several ways:

  • wear resistance. Mineral can be damaged by rough handling, but it gets polished. Sapphire is almost impossible to damage;
  • strength. With a strong impact, the sapphire crystal can be broken, the mineral glass is more resistant;
  • price. For the production of mineral glass, cheaper components are used, therefore the final price of mineral glass is lower than that of sapphire.

Is there any alternative?

Remember, watchmaking is constantly growing and developing. Today, leading brands offer affordable high quality products not only with sapphire crystals. What's the trick? Inexpensive mineral glass is coated with sapphire or anti-reflective effect is added. Many brands additionally temper the material, increasing the moisture resistance and strength of the glass and, accordingly, provide better protection for the dial and movement. It is true that "drugs" have not yet been invented because of the cloudiness of the mineral glass.

Visit to see for yourself: status accessories for any budget are easy to pick up in a few clicks. We guarantee professional advice and original quality.

If the watch dial has the inscription "Cristal", it means that its glass is made of minerals. The inscription "Hardlex" also indicates mineral glass, but the hardness of this composition is higher due to special processing. The “Sapflex” inscription indicates that mineral glass with a thin layer of sapphire was used for the manufacture of these watches. And what about a sapphire crystal from a mineral one, if there are no inscriptions on it?

Compliance with device class

First of all, the characteristics of the glass must correspond to the class of the device in which it is installed. Shockproof waterproof watches are most often equipped with sapphire crystals. Watches for everyday wear and sports are equipped, as a rule, with mineral and plastic glasses, less often with sapphire. You shouldn't expect that the device will be equipped with an expensive sapphire crystal.

How to distinguish expensive glass from simple mineral glass

You can put a drop of water on the glass. Tilting the watch with mineral glass in different directions, you can see that a drop of water spreads, leaving a trail behind it, the so-called tail. This does not happen with a drop of water on a sapphire crystal: even when the watch is tilted in different directions, the drop of water does not spread over the surface of the glass, but rolls over it like a mercury ball -. If the experiment is carried out with an anti-reflective sapphire glass, a drop of water will remain in the same place where it was placed, even if the device is turned upside down. The difficulty of the experiment is in choosing the right droplet size.

The second method of checking is not always possible when purchasing a product, for example, try to scratch the glass. The sapphire coating does not scratch, but breaks easily. In a store, you can check the glass for glare: mineral gives them, sapphire does not. If the watch is equipped with anti-reflective glass, it is not possible to find out whether it is sapphire or mineral, since both seem invisible, that is, they do not reflect light. Both the one and the other coating have a bluish tint.

The surest and most accurate way to distinguish one glass from another is to take turns bringing each glass to the tip of the nose and holding it for a few seconds. The colder material will be sapphire, as it heats up more slowly than the mineral. If both the one and the other will heat up evenly, then here we can confidently assert that both glasses are mineral. True, this experiment can be carried out with two devices, one of which is known for sure that it is equipped with a mineral glass coating.