# Hesalite vs Mineral vs Sapphire: Watch Crystal Comparison Guide
Choosing the right watch crystal is one of the most important decisions when buying or restoring a watch. This guide compares hesalite (acrylic), mineral glass, and sapphire crystal across hardness, clarity, impact resistance, scratch resistance, durability, and price.# Hesalite Crystal (Acrylic / Plexiglass)
Hesalite is the original watch crystal material, used since the 1930s. It is soft (2-3 Mohs) and scratches easily, but these scratches can be quickly polished out. It offers the best impact resistance - it flexes rather than shatters. Hesalite can be formed into extreme domes, giving vintage watches their characteristic look. Famous example: Omega Speedmaster Professional - the watch worn on the Moon.# Mineral Glass (Tempered)
Mineral glass is made from silicon dioxide and then tempered (heat-treated) to increase its strength. At 5 on the Mohs scale, it is harder than hesalite but still susceptible to scratches. It offers moderate impact resistance but can shatter on hard impacts. Commonly found in mid-range watches from Seiko, Citizen, and Orient.# Sapphire Crystal (Synthetic Corundum)
Sapphire crystal is made from lab-grown corundum - the same mineral as natural sapphire. At 9 on the Mohs scale, it is virtually scratch-proof and offers the best optical clarity. However, it is more brittle and can shatter on sharp impacts. It is also the most expensive option and difficult to form into high domes. The standard for luxury watches.# Crystal Comparison Table
| Property | Hesalite | Mineral Glass | Sapphire |
|---|---|---|---|
| Mohs Hardness | 2-3/10 | 5/10 | 9/10 |
| Clarity | 4/10 | 7/10 | 10/10 |
| Impact Resistance | 5/10 (Best) | 3/10 | 2/10 |
| Scratch Resistance | 1/10 | 5/10 | 10/10 |
| Repairable | Yes (polish) | No (replace) | No (replace) |
| Dome Possible | Yes, extreme | Limited | Limited |
| Price Range | $5 - $30 | $10 - $50 | $30 - $200+ |
Crystal Selection Guide
For a tool watch or daily beater, choose sapphire for scratch resistance. For a vintage restoration or budget build, hesalite offers authentic looks and repairability. Mineral glass is the budget-friendly middle ground found in most entry-level automatics.