Changing case sizes can be one of the most powerful tools in a watch designer’s arsenal when done well. Not only will a larger or smaller diameter take up more or less real estate on the wrist, but the proportions of nearly every element from hands to date windows, subdials, and even indices can evolve, changing a design that may feel too open and sparse at its largest size into something tight and balanced with a smaller diameter. IWC understands this principle well, as evidenced by the litany of various case dimensions it uses for its iconic pilot watch designs. On the dressier end of IWC’s lineup, however, sizing options have traditionally been more limited, and the Portofino Chronograph is no exception. For its latest release, the brand addresses this and dramatically shifts the character of the Portofino line in the process. Thanks to its compact new 39mm case, the IWC Portofino Chronograph 39 gives one of the brand’s most refined chronograph designs a compact, classic new feel, and a cleaner overall layout.

Naturally, the largest change to the new IWC Portofino Chronograph 39 is its 39mm stainless steel case. While the general concept of the design echoes the 42mm model, the decrease in diameter leads to a markedly different feel in initial images. The narrow straight lugs are set at the same width as on the 42mm model, but the decreased diameter of the surrounding case gives these lugs a more planted, athletic stance than on the larger variant. Likewise, the narrow mirror-polished bezel appears wider and more substantial here, still remaining light and slender but adding an underlying sense of solidity and visual balance. The softly rounded case sides help to reinforce the refined midcentury look of the design, as well. Perhaps the most divisive visual shift as a result of the resizing, however, will be the tall piston-style pushers. While these slim, brightly polished elements were sizeable on the 42mm model, here their brightly polished height will likely verge on oversized for some enthusiasts. In keeping with the classic look overall, the IWC Portofino Chronograph 39 features a simple vintage-style solid caseback with little in the way of ornate engraving. Despite the depth of this caseback and the 7750-based movement within, the Portofino Chronograph 39 boasts an eminently manageable thickness of 12.8mm, which should go a long way towards maintaining the watch’s dressy refined character on the wrist. IWC claims a water resistance of 30 meters for the Portofino Chronograph 39, but given its dressy connotations, this is less underwhelming than it might be for a sportier design.

IWC offers the iwc Portofino Chronograph 39 with a trio of dial options. The base dial design for all three is a simplified variant on the 42mm model, deleting the day/date window and removing the 9 o’clock subdial in favor of a clean two-register layout with subdials at 12 o’clock and 6 o’clock. As with the case, the smaller diameter of the dial gives these new dial designs a distinctly more balanced character in images. The shorter applied baton indices and cutout applied Roman numerals give the dial a more open, proportional feel, while the leaf hands appear slightly broader and more robust which should aid legibility. Rather than the multi-finish treatment of previous Portofino Chronograph models, IWC finishes the subdials of the Portofino Chronograph 39 with a more elemental full azurage treatment. While the subdial design might be more minimal here, IWC maintains the sense of dynamism and visual depth in images with a layered cutout look and brightly polished outer accent rings. Each of the three sunburst dial variants takes this blend of minimalism and classical warmth in a different direction, however. The silver dial model is the most traditional and reserved of the line, with an understated sunburst effect in images and gold-plated dial hardware that injects a touch of luxurious color to the mix. The black sunburst dial model shares these gold-plated elements, but a more aggressive grained sunburst effect in images and a deep charcoal-gray base tone give this model a more sporting and contemporary feel. The green dial variant, on the other hand, is by far the most attention-seeking of the three. The rich forest green sunburst tone feels perfectly on-trend in the midst of the current green dial explosion across the industry, and IWC’s decision to swap the gold plated hardware for bright rhodium plating gives the cooler green shade a bright neutral backdrop instead of a warm contrast with the gold.

Inside the IWC Portofino Chronograph 39 beats the Valjoux 7750-based Calibre 79350 automatic chronograph movement. IWC heavily modifies the base movement for the Calibre 79350, removing day and date wheels, deleting the 9 o’clock subdial, and moving the running seconds display from 9 o’clock to 6 o’clock. Power reserve performance is also slightly improved over the standard 7750, with a claimed 44 hours of reserve at a 28,800 bph beat rate. IWC finishes all three variants of the Portofino Chronograph 39 with glossy classical alligator leather straps. The silver dial model is paired with a strap in piano black, while the nuanced tones of the black dial are complemented nicely by a deep mahogany brown strap in images. Lastly, the green dial version is coupled with a dark, almost reptilian hunter green strap.