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The most complex single piece of
Sapphire in watchmaking.

A world-first sapphire skull with 100 more facets than a brilliant-cut diamond. Aventi is renowned for its control and mastery of sapphire, experience enabling us to make a more brilliant skull than anyone thought was possible.


We approached gem cutters worldwide, in India, Israel, and Thailand. There were no gem cutters that could cut this from a single sapphire, and they all said it was impossible. However, this is a vision we took to heart, so we took action ourselves. We used our experience in CNC machining sapphire, hand polishing, and watchmaking to do something they thought impossible. After one year of daily R&D driven by this goal proved the gem cutters wrong and produced the stunning sapphire skull.

2mm thick
2mm thick

Why was it so hard?

The sapphire skull has a thickness of only 2 mm, which means its edges and facets must be exact, within 0.005 mm. Driven by much time and effort, it is a proprietary process that no one had ever done before. The material is reset 48 times during cutting to reach every angle, each time with an increased risk of misplacement. Even the tiniest mistake would necessitate starting over. Sapphire is one of the worlds hardest materials. Every cut requires slicing from micron to micron with a diamond- tipped tool spinning at over 1000 RPM.


As an example of how complex the Aventi skull is, a brilliant-cut diamond has 58 facets, but our skull has 160. The creation of a skull of this calibre takes 16 weeks from start to finish, but making one mistake at any time means starting over.

You also need to consider the nature of sapphire - despite its hardness, it is very brittle. An incorrect tooling speed or slight pressure increase in polishing will crack the skull. A proprietary process was created to solve the risks and ensure perfection for every creation. Custom clamps, modified tooling and strategic cutting were all reinvented, just to name a few.

500 hours
500 hours

The creation of the Sapphire Skull takes 16 weeks from start to finish, but making one mistake at any time means starting over. There are 6 major stages to creating the sapphire skull.

Production Process
  • Stage 1
  • Stage 2
  • Stage 3
  • Stage 4
  • Stage 5
  • Stage 6
4 weeks Creating Pure Sapphire

Four weeks to grow the raw Sapphire using the Kyropulous method. Compressing a natural process completed over millennia into just 4 weeks. Pure aluminium oxide is melted at twice the temperature of molten lava, and a perfect single Sapphire is inserted into this molten metal. Over 4 weeks, this molten metal is slowly cooled as the Sapphire pulls from its surface, latching onto the Sapphire, the molten aluminium begins to crystalise and harden until a large single sapphire is formed.

1 week Preparing the Sapphire

Due to the hardness of Sapphire, we could not rely on conventional methods of machining. To crave out pieces of Sapphire into a workable size we use an unconventional process of Wire EDM

Wire EDM or Electronic discharge machining is the process of tensioning a thin wire, in our case tungsten, between two electrically charged diodes and placing it in contact with a conductive material.

6 weeks Machining the Sapphire skull.

A six-week CNC machining process using diamond-tipped tools with levels of accuracy smaller than a human hair. Using a 5-axis CNC machine, a piece of sapphire is carved and sculpted into an object more complex than any gem, within a tolerance of 0.01mm.

Sapphire is the second hardest material on the planet but in this strength lies its difficulty to be machined. A single mistake can cause catastrophic failure. Every cut of the sapphire skull requires 4-5 hours of machine setup and calibration.

With such a small margin of error, holding the sapphire presented its own set of challenges. The piece must be held perfectly still in a clamp in multiple positions, Apply too much pressure, and it will crack, not enough, and the piece will shattering losing hundreds of hours of work. A custom clamping system had to be developed to hold the skull as we could find nothing close to our requirements.

2 weeks Hand Polishing

Two weeks hand polishing all 200 faces and 160 facets with lambswool and wax to achieve the required clarity and consistency. Each process requires custom clamping systems that had to be developed and built in house.

2 weeks Anti-reflective coating.

Two weeks spent applying 14 layers of blue anti-reflective coating to ensure every perfect edge and every sharp facet are visible on the world's most sophisticated sapphire. As a result, when light hits the sapphire skull, it will dance across every facet whilst emitting a soft blue glow.

1 week Lume-printing

Lastly, Swiss lume is applied to the skull with absolute precision over one week, so even in the dead of night, you can feel the presence of the Sapphire skull. 7 layers of lume are individually applied. each printing must be allowed to cure for a minimum of 1 hour before being baked in an industrial kiln and allowed to cool. if a single line of lume is out by as little as 0.01mm the entire skull must be wiped clean and the process began again.

The sapphire skull in this watch is undoubtedly one of the most complex single pieces of sapphire in watchmaking, if not in the entire world— an omen of what is coming.

Aventi Specs
Material Sapphire of 99.99% purity
Tolerance 0.005mm
Number of facets and edges 160 facets, 200 edges
Thickness 2.3mm
Production method Custom CNC process
AR Coating 7 layers of blue anti-reflective coating on each side
Polishing By hand with custom made retention system
Production Time 16 weeks
A watch you
never see

Rival to all, bested by none.

CHF 13,750 Register your interest