On natural sapphire glass, a drop of water does not spread over the surface, but rolls like a ball of mercury. Another difference is that sapphire glass heats up more slowly than mineral glass.
If there is an inscription "Cristal" on the watch dial, it means that their glass is made of minerals. The inscription "Hardlex" also indicates the mineral origin of the glass, but the hardness of this composition is higher due to special processing. The inscription “Sapflex” indicates that for the manufacture of these watches, mineral glass with a thin layer of sapphire was used. But how can you tell 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. Don't expect an expensive sapphire crystal to be installed in a budget device.
How to distinguish expensive glass from simple mineral glass
You can put a drop of water on the glass of your watch. 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 - without a tail. 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 buying a product, for example, try to scratch the glass. The sapphire coating does not scratch, but it 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 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.
