There are basically three types of crystals, acrylic crystals which are used on some Fossil, Swatch, CWC and MWC watches, you tend to see them on retro or older models made up to the 1980s but some models still use acrylic for historical accuracy, examples are the CWC W10 and MWC A-11 and GG-W-113
You tend to find mineral crystal is the common in mid range watches and sapphire crystals are used in more expensive watches we will examine how to remove scratches for these below.
All crystals will wear over time but with the watches which we see at our service centre that come in for crystal replacement 95%+ of the watches have acrylic or mineral crystals, we have only seen two sapphire crystals shattered over the last 12 months so it can be worth the additional cost, of course lots of mineral crystals survive for many years but if you do break one a sapphire replacement is sometimes possible.
REMOVING SCRATCHES FROM ACRYLIC CRYSTAL:
This one's easy toothpaste will often work or there is polyWatch see https://www.polywatch.de/en/plastic-polish/
The repair process is very simple.
- Cover up the bezel if its a divers watch or if the scratch is in the centre you probably need not bother.
- Rub the polyWatch or toothpaste in a circular motion with a cloth. Another option is use an old electric toothbrush head.
- You might need to repeat this but the improvement with be quickly apparent.
THE WATCH BELOW IS A 1970s HAMILTON WITH THE SORT OF SEVERE SCRATCHING TO THE ACRYLIC CRYSTAL WE OFTEN SEE
Mineral crystals can be difficult to deal with and replacement can be an easier solution because the cost averages only £20/£25 or $27/$33 but polyWatch for mineral crystals is an option see https://www.polywatch.de/en/glass-polish/ if the scratches are not too bad this often works well.
Sapphire crystals are incredibly hard at 9 out of 10 on the Mohs mineral hardness scale, they are hard to scratch and diamonds are the only thing that scratches them easily. They are costly compared to mineral crystals but a lot of higher end manufacturers are moving towards these because it reduces the burden on their service centre to replace crystals. Although shattered crystals are not covered by warranty they tend to amount to around 50%-60% of service work and are very time consuming.
If you scratch a sapphire crystal there is a solution which often works see https://moldpolishing.engis.com/polishing-sapphire-crystal-case-study.html
We spoke to our watchmaker here at TSC who said he recommends 0.25 micron and 3 micron diamond polishing compound, we saw a set of 1, 3 and 6 micron pastes on Amazon for £20 its quite an arduous job on sapphire but if you have a suitable power tool and a small buff that will take most of the work out of it alternatively use an old electric toothbrush head.