Over the past 15 years, haute horologerie manufacturer MB&F has created some of the most visually distinctive innovative timepieces in its segment. Although the brand has fielded a wide variety of ultra-luxe models over the years, until now there has only been one MB&F offering in yellow gold: the LM101 Frost YG. Now, as part of the GPHG winning Legacy Machine Perpetual series, the marque has taken another rare trip into the realm of this material with the limited edition Legacy Machine Perpetual Yellow Gold.

The case construction of the Legacy Machine Perpetual Yellow Gold remains identical to its stablemates at 44 mm wide and a whopping 17.5 mm thick, but the introduction of 18 karat gold changes the presentation immensely. While on white gold, platinum, and titanium models the elemental and simplistic forms of the case fade elegantly into the background to give full attention to the intricate dial, the boldness and vibrancy of the new material demands to be seen, highlighting the mirror polishing and clean finishing at play. Perhaps the only minor gripe is the four small pushers at 2 o’clock, 4 o’clock, 8 o’clock, and 10 o’clock that disrupt the otherwise uninterrupted flow of the case, while recessing the pushers may have added a touch more class at the cost of easy functionality.

Like previous models in the line, the Legacy Machine Perpetual Yellow Gold is an intricate skeletonized weaving of elements that creates a stunning showcase for the movement within. Interestingly for an adaptation of an existing design, however, the dial of the Legacy Machine Perpetual Yellow Gold might be the most cohesive and harmonious of the line. Yellow gold accents throughout help to tie in to the case, with flashes of gold ringing the three calendar subdials at 3 o’clock, 6 o’clock, and 9 o’clock, the main time subdial at 12 o’clock, and most arrestingly of all, a fully gold rendition of the Legacy Machine’s signature oversized balance wheel hangs from the ornately sculptured bridge at the center of the dial. These gold accents are sharply contrasted by a brilliant sapphire blue base dial surface, which further ties into the blued hands throughout. While most of the complications on the dial are rather self explanatory, the unusual sweeping indicator at 7 o’clock may seem mysterious. This cryptically marked piece is actually a retrograde leap year indicator, with the one white dot indicating the need to make a simple one-button quickset on February 28 once every four years.

The bespoke handwound movement of the MB&F Legacy Machine Perpetual Yellow Gold is the brainchild of Northern Irish watchmaker Stephen McDonnell. This 581-piece powerplant features a unique “mechanical processor” instead of the traditional long lever system used in most perpetual calendars. This innovative system starts with a baseline length of all months at 28 days, then manually adds each extra day needed at the end of each month. This offers several benefits over a classical perpetual calendar system, avoiding the harsh skipping motion at the end of months with less than 31 days that can cause skipping or damage in many other movements while opening up the possibility for a skeletonized system with the massive hanging balance bridge shown here. Outside of the mechanical cleverness, this movement offers hours, minutes, day, date, month, a 72 hour power reserve indicator, and the aforementioned retrograde leap year indicator.

The bold luxurious finishing of the Legacy Machine Perpetual Yellow Gold continues in its array of hand stitched alligator leather straps, available in blue, black, gray, or brown. These straps are finished with a matching 18 karat yellow gold deployant clasp.

While the MB&F Legacy Machine Perpetual Yellow Gold may not bring any real innovation to the table beyond the use of yellow gold, it’s difficult to deny that the new pairing creates one of MB&F’s most striking and visually interesting color palettes. Only 25 examples will be made, retailing for $167,000. For more information, please visit the brand’s website.