“Z” is for Zalium. The unique alloy is at the heart of the tenth timepiece of the Project Z series, which sports an openwork dial and two complications.

The Project Z concept has been part of Harry Winston’s repertoire since 2004. The idea was to develop a collection inspired by aerospace and architecture, and use a special alloy exclusive to the American luxury goods house: Zalium.

The zirconium-aluminum alloy, as it turned out, was quite difficult to work with. But that hasn’t stopped engineers from managing to mill out entire watch cases out of a single block. The extra effort has been well worth it, since Zalium is very strong and at the same time very light and resistant to corrosion.

So far, nine limited edition timepieces have been released as part of Project Z by the Swatch Group brand. The latest addition to the Z family is the Z10, which draws its inspiration from Manhattan bridge in New York City. The collection has featured an increasingly mechanical aesthetic over the years, and the tenth model is a throwback to the early steel era.

Again, we have a 42.2mm case that is carved from a single block of Zalium, making the watch ultra-lightweight and ergonomic. And if the alloy wasn’t exclusive enough, it is mounted on a special Shuriken-marked dual strap that is composed of black rubber and blue alligator leather.

Part of the appeal of this watch is the contrast the designers have managed to achieve by using the powerful gray of Zalium with the deep blue of the dial structures. The frame of the dial features extremely fine openwork that is also made of deep blue anodized aluminum. One nice result is that we can appreciate the 18K white gold rotor at work.

For those of you already familiar with the Project Z series, you might have noticed that the hours and minutes are off-centre, something common across previous models. The hours and minutes counter is composed of a black grid and a black satin-finish chapter ring with rhodium markers.

The power comes via the automatic HW3305 movement, which also allows for two complications. The first is a retrograde day display at 4 o’clock and the other is a retrograde seconds display, on a scale of 0 to 30, at 8 o’clock. That means the hands travel only 120 degrees - instead of making a full revolution – and they automatically jump back to the start to resume their operation.

The Project Z10 is definitely true to the mechanical and metallic core that the series has become known for since its inception. And if you ask me, this latest addition is also a notable improvement in terms of the dial layout and depth of design when compared to the previous model, the Z9.