A domed acrylic crystal is part of the charm of a vintage Seiko, but it scratches easily. The good news: unlike glass, acrylic can be polished. Here is how to remove scratches from an acrylic watch crystal in about five minutes.
Is your crystal acrylic, mineral or sapphire?
| Crystal | Found on | Can you polish scratches out at home? |
|---|---|---|
| Acrylic (Hesalite, plastic) | Many vintage Seikos, some modern pieces | Yes, light to medium scratches |
| Hardlex (Seiko mineral glass) | SKX007, Prospex Turtle SRPE93 | No, replace if badly scratched |
| Sapphire | Higher-end models | No, very hard to scratch and to polish |
What you need
- A plastic crystal polish, such as Polywatch
- A clean, soft, lint-free cloth (any grit in it will add new scratches)
- Optional: painter’s tape to protect the bezel
Step by step
- Wipe the crystal clean so no dust is dragged across it.
- If the bezel is gold-plated or has an aluminium insert, mask it with tape. The polish is slightly abrasive.
- Put a pea-sized dab of polish on the crystal.
- Rub with the cloth in small circles, with even pressure, for 2 to 3 minutes.
- Wipe off and check under a light. Repeat for deeper marks.
What it can and cannot fix
- Fixes: scuffs, hairline and surface scratches.
- Improves but may not remove: deeper scratches you can feel with a fingernail.
- Cannot fix: cracks or chips. Replace the crystal.
Should you swap to sapphire?
On a vintage Seiko, think twice. A non-original sapphire crystal lowers collector value by around 5 to 15 percent, based on the factors in our vintage watch value calculator. A polished original acrylic keeps the watch correct.
Buying a vintage Seiko with a scratched crystal? It is usually a cheap fix, so focus on the checks that matter more: the dial, hands and movement. Our guide to spotting a fake Seiko covers them.
Frequently asked questions
Does Polywatch work on sapphire or mineral glass?
No. Polywatch’s plastic polish is for acrylic only. Craft + Tailored notes the brand’s diamond pastes for glass do not work nearly as well.
How do I know if my crystal is acrylic?
Acrylic is usually domed, feels warm and slightly soft when tapped with a fingernail, and shows a slight distortion at the edges. Many vintage Seikos use acrylic, but some use mineral glass, so check the reference.
Can toothpaste remove watch scratches?
Toothpaste is a mild abrasive and some people use it on acrylic, but a polish made for plastic crystals gives a more even result.
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