Mineral crystal or sapphire crystal, which one do you prefer? Let’s go through both of them in detail.
The glass of a watch is one of the elements that is most exposed to bumps, scratches, and scratches. The most common in recent years, where design is valued above many other things, is mineral glass.
In this part of the watch, the crystal can be designed and configured in many ways, such as rounded, domed, or even square. The main difference that we can find is also related to the chosen materials; among them, the most common is mineral or sapphire.
However, we also find plastic options such as plexiglass or acrylic hesalite glass.
As it is now so typical for the selling point of a sports watch to be its strength and durable dial, the materials chosen to protect the dial are important even if it means a higher production cost.
In this article, we want to show you the main differences between a mineral crystal and a sapphire crystal. There are clear differences regarding the price but, also regarding the quality, or is it a myth?
Read more: What are the parts of a watch?
Page Contents
WHAT IS A MINERAL CRYSTAL?
A mineral crystal is nothing more than a form of glass very similar to what we can have in windows or even in our glasses. Among the most common minerals is glass, made up of silica and other materials from rocks.
Although this element is more expensive than plastic glass, it is more resistant to shocks and scratches. Mineral glass is one of the most common options in most watches, leaving sapphire for the most expensive options.
When we heat the mineral-type glass to high temperatures, it is added greater resistance to scratching, something very common when we rub the watch against surfaces.
The biggest problem with this glass?
Without a doubt, scratched mineral glass is very complicated to polish or repair and it is better to replace it, and depending on the nature of the watch, whether there will be replacements or not.
WHAT EXACTLY IS A SAPPHIRE CRYSTAL?
Sapphire glass is the high line of dial protectors and is intended for the most expensive watches or luxury brands.
In fact, it considerably increases the cost of manufacturing the watch. Due to the properties it offers, it is highly appreciated in the world of watchmaking. It is manufactured by treating aluminum oxide at very high temperatures.
Due to the origin of the raw material, it has a much higher hardness than mineral glass similar to precious stones and the sapphire material itself.
THE COST OF SAPPHIRE CRYSTAL
One of the things that make the sapphire crystal more expensive is its manufacturing cost. The polishing of aluminum oxide requires very resistant materials since sapphire is extremely resistant.
In fact, it is rated at a value of 9 on the Mohs scale, so only materials like diamonds can break it. Hence, it is used for its resistance to protect the dial and all the contents, although only reserved for high-quality (and price) watches.
SAPPHIRE DISADVANTAGES
One problem that has a solution is that sapphire glass is much more reflective than mineral glass. This is a problem when we want to see the hours in high light exposure.
However, it is quite common for large watch manufacturers to incorporate anti-reflective coatings as a solution to this problem. To do this, they usually apply the primer just below the glass, so that the protective layer against bumps or scratches will never be lost.
HOW TO DISTINGUISH SAPPHIRE FROM MINERAL GLASS
Something very important when evaluating the quality of a watch before buying it is to distinguish between mineral glass and sapphire glass.
Temperature differences
Although we can always read the specifications, since it is a fairly common point to indicate it, there are also some tricks to differentiate between the two materials.
On the one hand, touch is important. Although both are crystals, the mineral does not absorb cold as much as the sapphire mineral.
Tear test
On the other hand, if the watch is already a few years old, it is normal for certain micro scratches or fissures to appear that are practically imperceptible if we do not apply a special type of light. With sapphire glass, these types of scratches should not appear, unless you work with diamonds, which is quite rare.
Of course, the test of trying to scratch it with a metal can also work, where the mineral crystal will suffer and be scratched. However, it is not something we can do on all watches so as not to affect their quality.
Incidence of light
Playing with the incidence of light, it is possible to obtain some blue tones in a mineral glass watch. However, the same does not happen with sapphire and we will only perceive subtle pink tones.
HOW IS THE CRYSTAL INSERTED INTO THE BOX?
Due to their hardness, sapphire and mineral crystals do not “flex”. Unlike plexiglass, they do not bend when inserted into a steel or titanium case.
For a sapphire and a mineral crystal to fit together, a gasket around it acts as a sealant for better water resistance. They are made of nylon that comes in either a straight linear ‘I’ shape or an angular ‘L’ shape to fit the crystal to the case.
The application of the gasket is quite simple. After a crystal, the pressing tool snaps the crystal into place in a watch case, the gasket squeezes the gap between the crystal and the edge of the case. This is one of the most durable waterproof options for a watch. Yes, these gaskets do break, so it’s best to replace them every few years.
SAPPHIRE OR MINERAL GLASS: WHICH TO CHOOSE?
Whenever possible, sapphire offers many more advantages than minerals. Especially when it comes to resistance, which is the most important condition to assess in a watch crystal.
If we cannot afford it or the model we like is not sapphire, the second option to choose is mineral glass. The latest technologies have considerably hardened this element and anti-reflective substances and greater hardness are applied to it.
BEST WATCHES WITH SAPPHIRE CRYSTAL
Finally, we would like to dedicate a space to some watches with an excellent quality/price ratio and that incorporate sapphire crystal. However, we are also obliged to incorporate luxury pieces that, yes, it is true that is not adapted to all audiences, but they are well worth seeing.
