Behold the HM3 Frog Zr, aka “Black Frog,” the newest highly limited watch from MB&F – there will only be 18 pieces. Unless I am mistaken, this is the first watch offered by the boutique brand done in zirconium (hence the Zr part of the name). Zirconium is a rare metal similar to titanium, but known to be more robust. According to MB&F, most zirconium is used in nuclear reactors and high-tech aerospace applications. There are a few high-end watches that utilize the exotic metal, and now MB&F has an interesting piece imbued with Zr.

The Black Frog is based on the HM3 Frog that came out last year. I discussed the piece more in this article. It is a variation on the MB&F HM3 that features two large domes under sapphire crystal that rotate to tell the hours and minutes. Being extremely popular, MB&F has been continually asked by fans to expand on the HM3 Frog theme. This newest one is probably the coolest Frog so far in my opinion (though I did really like the Chocolate Frog a lot).

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In nature black frogs exist, but what about black and purple ones? I discovered that they indeed do. In 2007 a new species of Atelopus frog in Suriname was discovered by scientists to be black with florescent purple stripes. I wonder if MB&F was aware of this little guy when designing the Frog Zr watch – in any event it is a great mascot for the timepiece and a beautiful creature.

The Black Frog’s zirconium case is coated black. The weight of zirconium is similar to that of titanium and the look of the case is fantastic with the purple coated 22k gold rotor for the automatic movement. MB&F shared with me an interesting story about the purple color. MB&F was with a supplier and interested in new colors that were available. They were told of a purple color, but advised against using it because it was “unstable.” Immediately intrigued, MB&F asked what they meant. Basically the metallic purple color didn’t maintain the same purple tone in all angles. Even though the supplier thought no one would want the color, MB&F realized it would be perfect for the battle ax style rotor – and it is. The purple rotor is really the star of the design – appearing to change colors all the time.

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Attached to the black alligator strap the Frog Zr is a good looking timepiece and exudes a smooth sort of confident coolness. Limited to 18 pieces, the MB&F HM3 Frog Zr will be available soon – for a retail price of $92,000.

HM3 Frog Zr — Technical Specifications

HM3 Frog Zr is a limited edition of 18 pieces



Three-dimensional horological engine designed by Jean-Marc Wiederrecht/Agenhor;
Powered by a Girard-Perregaux base

Balance oscillating at 28,800 bph.

Purple 22K rose gold battle-axe shaped ‘mystery’ automatic winding rotor

Hour and minutes information transmitted via ceramic ball bearings to rotating domes.

Number of jewels: 36 (all functional)

Number of components: 304


Hour on one dome (aluminium dome rotating in 12 hours)

Minutes on second dome (aluminium dome rotating in 60 minutes)

Date around the movement


Zirconium; limited edition of 18 pieces

Screwed-down crown

Dimensions (exclusive of crown and lugs): 47mm x 50mm x 16mm

Number of case components: 53

Sapphire crystals:

Domes and both display backs with anti-reflective treatment on both faces.


Rotating aluminium domes — 0.58g, stationary hands

Strap & Buckle:

Black hand-stitched alligator strap with 18K white gold & titanium custom designed deployment buckle

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