The Well-Made Watch: The Crystal

When looking for quality, there are several characteristics of a well-made watch. The crystal or glass is another one to focus on as many affordable watches will offer several different materials. There are 3 main types of crystals that can come with a watch: acrylic, mineral glass and sapphire crystal. 

Before jumping into the crystal types, let's touch on how we can measure the scratch resistance of a material. This is important in a watch since we want to be able to see the dial clearly and not have imperfections on the crystal. The Mohs Hardness Scale can be applied to quantify how scratch resistant a crystal will be or how likely you will see scratches on your crystal after a bump. This is a rough scale and is from 1 to 10 with 10 being the most scratch resistant (aka diamond). 

Acrylic is an engineered plastic and can be seen on several vintage watches since it was most commonly used up until the 1980s. Another name for Acrylic is plexiglass and is known for its flexibility or strong impact resistance. On the Mohs Hardness Scale, Acrylic is about a 3 or a 4 so you can expect to see scratches in the crystals and can become cloudy over time. The silver lining is the cloudiness and scratches can be buffed out if not too deep. Another benefit of this crystal is, it will not shatter like glass if it does break. This is a good quality when it comes to protecting the other parts of the watch or your skin. This crystal is the cheapest to manufacture out of the 3 so you can see it on a lot of low budget watches; however, surprisingly that does not mean that high end watches will not use this crystal for some of their models. So when it comes to determining watch quality, if a watch comes with an acrylic crystal, that does not automatically mean the watch is made poorly. Look at the other characteristics in conjunction with the crystal to see if a watch is well-made. If you have a high end watch with an acrylic crystal, safe bet it's a good watch. If you have a budget watch with an acrylic crystal, that might not be a good sign. 

Mineral Glass is the most common watch crystal on the market today and is relatively cheap to manufacture. It is a glass made from silica that is heat treated to increase its scratch resistance. Sometimes you will see it called Hardlex but that is just a type of mineral glass made by Seiko. Mineral Glass ranks about a 5 on the Mohs Hardness Scale so it is more scratch resistant than acrylic; however, it is less flexible and will chip if broken. Despite this, it does has some strength and protection from completely shattering. Another positive of mineral glass is, like acrylic, it does not have much of a glare. However, unlike acrylic, you cannot buff out scratches and will sooner or later need to be replaced. From a quality perspective, most new low budget watches will have this crystal on their pieces. Even though mineral glass has some good things going for it, it is definitely not the best out there. 

Sapphire crystal is the hardest to manufacture out of the 3 and therefore the most expensive. It is made by applying high heat and pressure to aluminium oxide powder then heat treating the crystal. Most commonly made in a lab, it can also be referred to as synthetic sapphire. This crystal is most commonly used on high end watches due to its scratch resistance and is expected to last a very long time without seeing any imperfections. This crystal is the most scratch resistant out of the 3 scoring a 9 out of 10 on the Mohs Hardness Scale. So, it can be scratched but only with a very hard material like a diamond. There are some downsides to this material. It is the worst crystal when it comes to impact resistance and has a higher probability to shatter. It also has a high reflection of light so you can see a glare in the crystal when the light hits it at the right spot. Nevertheless, the crystal looks great, still very strong and is the preferred crystal on a watch. 

                  

The crystal is not the only characteristic to consider when looking for a quality watch but it's definitely something you should consider. Examine the Case Material, Movement and Water Resistance to round out what to look for in a well-made watch.