Glass – an integral part of the clock from the moment they c towers came down in our pockets and then moved to the wrist. The original glass is made from rock crystal, and then the chemical industry development has made it possible to replace it with artificial resins, celluloid, polycarbonate and others.
Currently, the most common, in addition to Plexiglas, mineral glass, which is melted quartz sand treated in a special way. For more expensive models are watched with sapphire crystal.
Of course, this is not the natural stone, mined in the tunnel, and its synthetic analog, synthesized in the laboratory.
The first thing you can do to determine how the glass is provided with a model you are interested in – pay attention to the markings on the dial or the back of the watch. Of crystal Sapphire’s – so mark sapphire glass, the mineral often not designated at all, or are mentioned as of crystal glass. However, to protect them from counterfeiting and just feel like a connoisseur, you can try a few simple ways.
Apply a drop of water on the glass for the experiment. The most convenient way to do it the conventional pipette, so you do it carefully and will be able to regulate the droplet size. Now try to tilt the clock continuing to closely monitor the water, its “behavior” will answer. If a drop sliding down the glass, leaving a distinctive footprint, like smearing, this mineral. If it resembles mercury bulb and remains in this state during rotation, before you sapphire. By the way, on the glass with anti-reflective coating drop of water can freeze at all and does not slide off, even if you turn them down the glass.
The tip of the nose
For the purity of the experiment will need to watch and sapphire and mineral glass, although the general conclusion can be drawn on the same model, especially if you spend this experience is not the first time. Sapphire crystal has a lower thermal conductivity, and hence the longer it will cool down. The tip of your nose – the most precise tool in this situation. Put the clock for a moment in front of him, then take them one by one, tap the glass nose – that was cold, made of sapphire. Mineral quickly reaches ambient temperature, you do not even feel it. We should not expect a big difference, if you inadvertently left the clock in the sun, the sapphire too hot.
Scratches and bumps
Sapphire glass is known for its hardness, so many directories clock with glass labeled as “scratch-resistant” and it’s true. On the Mohs scale (hardness scale) sapphire and synthetic analogs occupy the 9th place out of 10, only a diamond can cope with it. Scratches are not afraid of him, but that’s a good punch, it is unlikely to survive.
Watches mineral glass, on the other hand, is easy to parry a blow, but are afraid to scratch, so that they have to be vigilant to protect. One happy: some watch glasses amenable to polishing, but it all depends on from which it is made the concrete material. The epic and bloody battle “against the mineral sapphire” (collector it could only have imagined in a nightmare) wins a blown glass of mineral, but Sapphire is the able opponent to full opacity.
An additional factor that allows you to understand what material holds the glass, – the price of products. Sapphire glasses are expensive to manufacture and decently increase the final cost. By the way, this is why square and rectangular clock with glass noticeably more expensive than their counterparts in a round case, because the initial blank should be larger and in the process waste takes more cut pieces. Artificial sapphire is more difficult to process, and it is necessary to throw out all of the workpieces at the slightest marriage. Glass of mineral easier conceived to give shape watchmaker, so the vast number of hours with a convex or curved glass makes it out of him.