High-End Apple Watches Use Sapphire Crystal Glass, original image from gearopen.com
As the window to your timepiece, the watch crystal takes some of the hardest hits, and the brunt of the everyday wear and tear. To extend the life of your watch crystal, crystals are made of different materials to ensure different kinds of strength. Plastic crystals are the most flexible of all the watch crystals, and therefore are used in a wide range of watches. Glass crystals are also common in watches.
The wonderful thing about plastic and glass crystals is the fact that they can be custom cut, shaped, or trimmed to fit different watch cases. Typically in the luxury watch field, sapphire crystals are preferred. Sapphire is extremely strong and scratch resistant - making it the top choice for a fine timepiece. There are three main types of crystals used in watches: sapphire, mineral and acrylic.
Acrylic Crystal
Acrylic is similar to plastic. It is light, durable and affordable type of crystal but prone to scratches. Acrylic crystal is mostly used for children watches, but not for fancy timepieces. Acrylic crystals have a unique advantage among other types of crystals: it can be polished to remove tiny scratches.
Acrylic Watch Glass, image from eurowatchglasses.co.uk
Mineral Crystal
Mineral crystal, also known as "Hardlex", is actually ordinary glass which has been heated and chemically treated to increase scratch and shatter resistance. Mineral crystals are quite durable but less durable than acrylic crystals.
NEW Seiko 5 SPORTS SRPD69K1 (FLAT HARDLEX CRYSTAL), Super-J Louis bracelet by MiLTAT
They will get some scratches eventually and they're not as easy to maintain as acrylic crystals. The cost for mineral crystal is quite cheap, so people would often replace the glass instead of having to worry about damaging the glass. Mineral crystals are mainly used on low-middle class watches.
Sapphire Crystal
Pros & Cons for the three common types of watch crystals
Acrylic Crystal
- Easy to manufacture and manipulate to whatever shape desired
- Inexpensive to produce; cheap to replace
- Simple to re-polish
- It won't shatter or break easily. When it does break, generally it will crack, but stay in place, -protecting the wristwatch's dial and movement from further damage
- It scratches easily
- Lots of scratches can impact visibility, and then will require the owner's efforts to either re-polish or replace the crystal
Mineral Crystal
(Watch Models Used) New 2019 Seiko 5 Sports line-up of 27 models, SRP Turtles
- Looks similar to sapphire at a fraction of the cost
- Not as brittle as sapphire
- It's much more scratch resistant than acrylic glass
- Can be coated to increase scratch resistance
- Less expensive replacement crystal when repairing watches
- Scratches easier than sapphire
- Won't withstand impact as well as acrylic glass
- Harder to polish than acrylic glass
Sapphire Crystal
Watch Models Used (Emperor Tuna SBDX013, 200MM Baby Mariner Master SPB109J1, SBDC079)
- Superior scratch resistance. Only moissanite (9.25) and diamonds (10)exceed its hardness ranking (9) on the Mohs scale
- Exceptional clarity
- Use of an Anti-reflective coating makes the crystal seem to disappear
- Synthetically made
- Most expensive option
- Prone to shattering due to its brittle nature
- Difficult to polish
How to Tell the Difference Between Watch Crystals
There are several ways to check what type of watch crystal you have on your watch, and its actually quite simple.
Acrylic Crystal - Clouded & abundance of scratch marks, produce a plastic-like sound when tap on the surface with your finger
Mineral Crystal - Clearer view than acrylic crystal, less scratch marks, product a high-pitch sound (sounds like tapping on glass), blue color, water will be divergent when drop on mineral glass
Sapphire Crystal - exceptional clarity, scratch free even against the likes of metal objects, easy to chip & shatter, water drop will flock together on sapphire crystal, pink/white color
Water drop test on Hardlex Crystal / Mineral Glass on Seiko SKX007 vs Sapphire Glass on Seiko MM300 SBDX017
Once you decide on the properties of watch crystal you prefer to use, you then have to decide on the design of the glass to go with. There are three types of watch crystals designs that are commonly used when it comes to selecting the shape/cutting of the watch crystal.
Crystal Design
When it comes down to deciding on which design to use on your watch, it really depends on your personal preference. Some people may prefer the basic flat design, so they would not have to worry about banging or damaging the glass with wear and tear when worn on a regular basis. Some people may prefer to go with the single dome design, which enables magnification factor. However, some may be even willing to pay extra to go with the double dome design, simply because they like the looks of it.
Single Dome - domed top surface flat underside magnifies a little bit and the crystal distorts the dial at extreme angles.
Double Dome - round on the outside and inside which means it does not have any or just very little distortion when looking at the watch dial from an angle. It's more expensive to produce but I think they look a lot better.
Ways To Remove Scratch Marks On Watch Glass/Crystal
- Identify the type of crystal on your watch
- Select the appropriate polishing agent (different for each glass/crystal)
- Contact manufacturer if uncertain of which crystal used on watch
- Use painter’s tape to protect the watch to avoid damage during cleaning process
- Apply a small amount of polish on the cracks and scratch marks on the crystal and rub it with a soft cloth for a few minutes
- If the scratch mark is too deep and not removable, can use a stronger polish agent, or consider to replace the watch glass
Unavoidable scratches on your watch glass are bound to happen over time. However, with proper tools, and various polishing agents, (depends on type of crystal), and a few guide lines to look out for, minor scratch marks can be removed. If the scratch mark is too deep, and not removable even after buffing and polishing the crystal repeatedly, replacing a new crystal would be the only alternative option.
Read more articles below :
- Ways to Polishing Scratches from Your Watch Crystal
- Ways to Remove Scratches From a Watch With Toothpaste
SRP Turtle Double Domed Sapphire Crystal, image from namokimods.com
The three watch crystals mentioned above that are used often today remain incomplete, as each crystal have their strengths and weaknesses. While acrylic crystal can sustain the most damage among the three types of watch crystals, its downside results in clarity and scratch resistance. As for mineral crystal, although it is cost efficient, as well as heated and chemically treated to strengthen the crystal, they are not as durable as acrylic or sapphire crystal. Sapphire crystal will remain as the top choice when it comes to the selection of watch crystal because of its clarity, strength, and scratch resistance, which will allow your watch to remain in top condition for a very long time.
Written by Sam , photo by Toni & other sources as noted
References URL:
- Apple Watch scratch resistance: Ion-X vs. sapphire glass - SlashGear
- Watch Crystal Types: The 3 Common Crystals
- How to Remove Scratches From a Watch With Toothpaste
- Polishing Scratches from Your Watch Crystal
- Crystaltimes Horology - The BEST Source For Sapphire Crystals And Seiko SKX Crowns
References videos:
For more details regarding watch crystals, please check out the following video link: Youtube videos @Lume Shot
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