HM9 Sapphire Vision watch puts intricate movement in full view

High-end watchmaker MB&F has released a limited edition of its Horological Machine No. 9 (HM9) wristwatch called the "Sapphire Vision, which sets the movement inside a specially engineered, transparent, three-dimensional sapphire and precious metal case to show off the works.

In 2018 MB&F added the HM9 Flow watch to its spectacularly outrageous portfolio. The HM9 boasted a case intended to echo the lines of the classic cars and aircraft of the 1940s and '50s. It was a nice bit of whimsy, but the company wasn't satisfied because the titanium case hid the mechanics, which MB&F founder Maximilian Büsser described as "the most beautiful movement we’ve created to date."

To correct that apparent shortcoming, MB&F has come up with the Sapphire Vision, which, as the name implies, replaces the titanium case with one sculpted out of sapphire. Such cases have been made before, but these tend to be rather boxy affairs because, though extremely hard, sapphire fractures when put under pressure where metal will deform.

To get around this problem and to recreate the shape of the HM9 Flow, MB&F had to make some slight redesigns to reduce the pressure on the case and treat the sapphire crystals, putting in about 350 hours of careful machining and polishing in the process. A patented 3D rubber gasket joins the case around the movement and the three sapphire pieces were fused to the metal frame using a vacuum and high temperature process then sealed with a special bonding compound. The result is a 52-component case water resistant to 3 ATM (30 m, 100 ft).

But the case isn't made to be seen so much as to be seen through. It's main purpose is to show off the 52-jewel, 301 component, manual-wound movement that uses a single-barrel 45-hour power reserve to run two independent balance wheels beating at 2.5 Hz (18,000 bph). This may seem slow in a precision caliber, but the two balances are averaged by planetary differentials to produce a more accurate readout on the vertical dial display, while cancelling any resonance that might develop.

In addition, there are dual spherical turbines under the movement and shock-absorbing helicoidal springs between the movement and the case. To produce these, MB&F used lasers to cut the springs out of solid tubes of stainless steel for better elasticity and limited lateral displacement.

The HM9 Sapphire Vision will put you back a tidy US$440,000 and comes in four limited editions of five units each. Two editions come in a 18K red gold frame with a NAC-coated black or a PVD-coated blue engine, the other two editions in 18K white gold frame with a PVD-coated purple or a red gold-plated engine. Both come with a brown or black alligator strap with a matching red or white gold folding buckle.

The video below introduces the HM9 Sapphire Vision.

Source: MB&F