Choosing the right gasket type depends on the sealing zone (crystal, case-back, crown) and the assembly mechanism. This comparison guides you.
Comparison table of the 4 types
| Type | Material | Section | Main use | Life | Price |
|---|---|---|---|---|---|
| O-ring | NBR / silicone | Round (torus) | Screw-down back, crown | 3 - 5 years | € |
| Flat | Rubber | Rectangular | Snap-on back, clasp | 2 - 4 years | € |
| Red | Rigid silicone | Dedicated profile | Mineral / sapphire crystal | 5+ years | €€ |
| Soft silicone | Silicone Shore 70A | Variable | All-purpose, diving | 5 - 8 years | €€ |
How to choose the right gasket?
For the case-back
O-ring if the back is screwed (the thread compresses the gasket). Flat if the back is snap-on (pressure held by the bezel).
For the crystal
Red gasket as standard. Rigid material that holds the mineral or sapphire crystal in place under bezel pressure.
For the crown
Cylindrical O-ring of small diameter. Its flexibility allows the stem to move while staying water-tight.
Mistakes to avoid
- Replacing an O-ring with a flat gasket: the compression geometry does not work.
- Choosing silicone for everything: costly and useless for non-immersed use.
- Not measuring before buying: a gasket that is too large does not compress, one too small forces against the part.
See the guide measure a gasket before buying.
"A watch's water resistance relies 90% on the condition of its gaskets, not on the quality of the case."
Frequently asked questions
How much does replacing all the gaskets cost?
Between 5 and 15 € for the gaskets themselves, plus 30 to 80 € in labour if you go through a watchmaker.
Can an old gasket be reused?
No. Any removed gasket must be replaced. Its initial deformation does not return to a sealing shape after reassembly.
Which gasket lasts the longest?
Well lubricated Shore 70A silicone gaskets last 5 to 8 years under normal conditions.