Sapphire glass

Sapphire crystal is now a symbol of quality and durability in modern watchmaking. However, its history is much more recent than one might think, and it has revolutionized the way high-end watches are designed.

Here is a clear and comprehensive summary of its history, evolution, and technical characteristics.

1. Origin and invention

Late 19th century – the creation of synthetic sapphire

• Sapphire is a natural gemstone (crystallized aluminum oxide, Al₂O₃).
• In 1902, French chemist Auguste Verneuil developed a process for synthesizing sapphire through high-temperature melting: this is the Verneuil process, which is still used today.
• This process makes it possible to produce pure synthetic sapphire, identical to natural sapphire but much less expensive.

At that time, it was mainly used for scientific and optical applications (lenses, lasers, measuring instruments), but not yet in watchmaking.

2. Introduction to watchmaking

1930s–1950s: the first experimental uses

• Some military and scientific watches test sapphire crystal for its resistance.
• However, the cost and difficulty of manufacturing limit its use.

The 1970s: democratization with quartz and luxury

• With the rise of quartz watches (which are more accurate and slimmer), brands are looking for more resistant and transparent crystals.
• Brands such as Rolex, Omega, and Audemars Piguet are beginning to use sapphire crystal in their high-end models.
• Sapphire is gradually replacing:
  • Plexiglas (acrylic): inexpensive but fragile,
  • and mineral glass: harder, but susceptible to scratches.

1980s–2000s: high-end standard

• Industrial advances have made it possible to produce thinner and more precise sapphire ice.
• Luxury brands (Rolex, Patek Philippe, Tag Heuer, Breitling, etc.) are adopting it en masse.
• It becomes a symbol of prestige and quality.

Since 2010: modern innovations

• Sapphire is no longer reserved for luxury watches:
  • Many mid-range brands use it.
  • We are seeing the emergence of cases made entirely of sapphire (Hublot, Richard Mille, Bell & Ross, Czapek, etc.).
• New colors (blue, red, smoked, transparent) are now possible thanks to chemical treatments.

3. How sapphire ice cream is made

1. Melting of pure alumina powder (Al₂O₃) at 2000 °C.
2. Slow crystallization into a “ball” (synthetic sapphire ingot).
3. Cutting the ingot into thin sheets using industrial diamond tools.
4. Polishing and anti-reflective treatment on one or both sides.

The result: ultra-transparent, hard, and durable glass with a hardness of 9 on the Mohs scale (only diamond scores 10).

4. Advantages and disadvantages

Advantages

disadvantages

5. Comparison with other types of lenses

6. In summary

Synthetic sapphire marked a major turning point in the history of watchmaking:

It has made it possible to combine durability, clarity, and prestige, definitively replacing mineral glass in high-end watches.

Today, it is a technical and aesthetic standard, symbolizing modern watchmaking perfection.