Optical Protection & Hardness

Custom Watch Crystal OEM & ODM Manufacturing

Synthetic sapphire crystal and hardened mineral glass manufacturing for luxury timepieces and rugged tool watches. We produce flat, single-domed, double-domed, and vintage box sapphire crystals featuring multi-layer anti-reflective coatings.

Factory Production Benchmark

  • Substrate Material Synthetic Corundum Sapphire (Al2O3) or Hardened Mineral
  • Hardness Rating Mohs Hardness 9 (~2000 Vickers Hardness)
  • Crystal Geometries Flat, Single-Dome, Double-Dome, Box-Type
  • Anti-Reflective Coating Internal Multi-Layer AR (Clear, Blue, or Anti-Fingerprint)
  • Edge Finishing Stepped Bevels, Diamond Chamfered, Polished Rim
  • Thickness Band 1.2 mm (Dress) to 4.5 mm (Deep Diver)
  • Sample Lead Time 18 to 22 Working Days
  • Inspection Standard Interferometer Flatness & Scratch-Dig 40-20
Manufacturing Scope

Crystal Profiles & Optical Formats

Engineered for exceptional clarity, impact durability, and distortion-free viewing.

Vintage Optical Depth

Double-Domed Sapphire Crystal

Curved on both top and bottom surfaces with identical radius, eliminating optical edge distortion and allowing clear dial legibility from acute angles.

  • Optical Distortion Zero edge distortion at extreme angles
  • Coatings Multi-layer internal anti-reflective coating
  • Profile High curvature dome with bevelled shoulder
Mid-Century Heritage

Box-Type Vintage Sapphire

Recreates the distinctive aesthetic of vintage acrylic crystals with a vertical cylindrical wall rising above the bezel and sharp step bevels.

  • Aesthetic Warm vintage silhouette with modern scratch resistance
  • Machining Diamond ground from thick sapphire boules
  • Thickness Up to 3.8 mm total height
Extreme Deep Ocean

Heavy-Duty Diver Sapphire (4.5 mm)

Ultra-thick flat or domed sapphire discs engineered to withstand hydrostatic pressures up to 100 ATM (1000M) without deflection or micro-cracking.

  • Thickness 3.5 mm to 4.5 mm solid sapphire
  • Pressure Tested 125% hydrostatic overpressure test
  • Gasket Seating Precision I-ring or L-ring gasket mating
Engineering Precision

Watch Crystal Optical Specifications

Strict dimensional benchmarks, alloy specifications, and verification methodologies applied to every manufacturing run.

Optical Property Synthetic Sapphire Benchmark Hardened Mineral Glass Test Protocol
Surface Hardness Mohs 9 (~2000 HV) Mohs 6.5 (~700 HV) Diamond indenter Vickers hardness test
Light Transmission > 99.5% with double-sided AR ~90% standard reflection Spectrophotometer light transmittance scan
Refraction Distortion Zero distortion on double-domed geometry Minor distortion on deep single dome Optical grid distortion camera audit
Hydrostatic Resistance Withstands > 100 ATM at 4.0 mm Rated up to 20 ATM Water pressure compression chamber test
Manufacturing Protocol

Precision Production Workflow

From technical CAD validation to cleanroom quality inspection, our engineering workflow ensures strict repeatability.

PHASE 01

Engineering DFM & Blueprints

Our engineers inspect your 3D CAD files or reference samples to optimize wall thicknesses, gasket compression tolerances, and tooling paths. Comprehensive manufacturing blueprints are delivered for review.

PHASE 02

Master Prototyping & Testing

First-article prototypes are machined via 5-axis CNC and assembled in our cleanroom. Each prototype undergoes dimensional verification, dry vacuum and hydrostatic water testing, and hand fitment audits.

PHASE 03

Precision CNC Machining & Finishing

Batch manufacturing utilizes multi-axis Japanese CNC equipment, robotic surface polishing, and master hand-applied satin graining. Components undergo strict optical inspection before movement casing.

PHASE 04

Class 10,000 Cleanroom Assembly & QC

All watch casing and critical sub-assembly takes place in ISO 14644 Class 10,000 cleanrooms to eliminate airborne dust. Every completed piece passes 48-hour mechanical timing and dual pressure tests.

Procurement Guidance

Frequently Asked Questions

Common technical and commercial questions regarding custom horology manufacturing and private label supply.

Why is sapphire crystal preferred over mineral glass?

Synthetic sapphire has a Mohs hardness of 9, making it virtually scratch-proof against everything except diamonds and silicon carbide.

What is the difference between single-domed and double-domed sapphire?

Single-domed crystals are flat on the bottom, which creates optical magnification and distortion at angles. Double-domed crystals have matching curves for distortion-free viewing.

Why do you apply anti-reflective (AR) coating on the underside only?

Applying AR coating on the inside prevents the coating from being scratched by everyday abrasive contact, preserving sapphire’s lifelong clarity.

Can you produce sapphire caseback crystals for exhibition watches?

Yes. We manufacture flat and stepped sapphire crystals for casebacks, allowing clear views of movement rotors and finishing.

Start Your Production Project

Bring Your Horological Vision to Reality

Send us your 3D CAD drawings, component blueprints, or design concepts. Our horological engineers will prepare a comprehensive casing analysis, tooling proposal, and quotation within 24 business hours.

Submit Request for Quotation