If you’re shopping for a new smartwatch or fitness tracker, you may have come across the term “sapphire glass”. But, what is sapphire glass?
Read on to discover everything you need to know about sapphire glass, including what it is, how strong it is, how it’s made and which smartwatches have it.
What is sapphire glass?
Sapphire glass is a material used in the displays of luxury watches and high-end smartwatches, including ones from brands like Apple, Huawei and Garmin.
How strong is sapphire glass?
One of the biggest benefits to sapphire glass is how durable it is.
Sapphire is a nine on the Mohs hardness scale (to put that into context, diamond is the hardest at 10). This makes it significantly more scratch and crack resistant than the glass used in larger devices, like smartphones.
It’s also tougher than cheaper materials used to produce watch crystals, including acrylic glass and mineral glass.
Sapphire glass is ideal for devices that are subject to a lot of wear and tear, like smartwatches and fitness trackers. It’s also commonly used in smartphone camera lenses, protecting them from getting scratched or scuffed and ruining your photos.
How is sapphire glass made?
Sapphire glass isn’t technically a glass, but a synthetic material made out of aluminium oxide.
Sapphire glass is produced by mixing aluminium oxide, a “sapphire seed” and uncrystallised sapphire and placing it in a furnace. The materials are then heated to 2200°C, left to cool for around two weeks and cut into paper-thin, clear sheets.
One drawback to sapphire glass is that it’s more expensive to produce than other durable displays, like Gorilla Glass. This is why it’s rarely used to cover larger areas – like smartphones and tablets – as well as why you won’t see it on every wearable on the market. This is why outside of watches, phones only tend to use it to protect their rear camera housings.
Which smartwatches have sapphire glass?
Apple Watch’s that feature stainless steel, titanium and ceramic cases are made of sapphire glass. This includes the Apple Watch 7 all the way back to the Apple Watch 2. The lower-end aluminium models use Ion-X glass instead.
Other popular smartwatches and fitness trackers that contain sapphire glass include the Withings ScanWatch, the Huawei GT 2 Pro and a handful of Garmin wearables, including the Fenix 6 and Fenix 7 Sapphire Editions. Based on our experience testing the device we’ve found the use of sapphire glass is a serious bonus. Reviewing fitness trackers, such as the Fenix 7, the more rugged glass let the wearables survive experiences that would shatter Gorilla Glass, such as being smacked into a rock on a climbing wall. Which is why we always tend to recommend more adventurous users on the hunt for a fitness tracker invest in one with sapphire glass.