Nomos has spent thirty years arguing that a watch does not need to be large to have presence, and the square Tetra has always been the sharpest version of that argument. The newest additions push it further. The Tetra 27 white and the Tetra 27 duo are the two smallest square watches the brand makes, each measuring 27.5mm on a side and 6.1mm thick, and both were introduced by Monochrome as permanent-collection pieces rather than limited runs.
Why 27.5mm is not as small as it sounds
Geometry does some of the work here. At an equal width, a round watch covers roughly 78 percent of the area of a square one, so a 27.5mm square reads larger on the wrist than the number suggests. Nomos sizes most of its Tetra models around 30mm for exactly that reason, and even the 33mm Tetra Neomatik does not wear small. Asked directly, Monochrome's Brice Goulard put the Tetra 27 at about the wrist presence of a 33mm round watch, since the lug-to-lug stays close between the two shapes while the square fills more of the eye.
The case is framed by a narrow polished steel bezel, with the double-stepped lugs that give the Tetra its Art Deco line. A sapphire crystal sits over the dial, and the buyer chooses between a solid steel caseback and a sapphire one. Water resistance is 50 metres, which is more than the proportions imply.
Two dials, one classic and one quieter
The Tetra 27 white is the most Nomos dial there is. It is a silver-plated, galvanised surface with a small seconds counter, the Arabic numerals and markers shared with the Tangente, and blued steel hands. The one change from the long-running 29.5mm hand-wound Tetra is the small seconds, now a flat round sub-dial in place of the old recessed square one.
The Tetra 27 duo removes the seconds hand and adds depth instead. Its galvanised dial carries a two-tone effect, a light grey square marking the centre with a matching grey field around the minute track. The two-tone treatment has existed before in a 29.5mm version with small seconds; here it comes in the smaller, cleaner two-hand format.
The movement is the reason to look closer
Both watches share the hand-wound Calibre DUW 4001. It is an evolution of the Nomos Alpha, itself an in-house rebuild of the old Peseux 7001, and the family resemblance is now mostly historical. The DUW 4001 uses entirely different bridges built as a three-quarter plate, and it is finished with Glashuette ribbing, perlage, a double-sunburst ratchet wheel and blued screws. It runs the in-house Nomos Swing escapement with its blue balance spring, adds a stop-seconds on the white version, and holds 53 hours of reserve at 21,600 vibrations per hour. The movement measures 23.3mm by 2.6mm, which is part of how the case stays thin.
Price and availability
Both models come on a black Horween shell cordovan strap with an 18mm lug width and a steel pin buckle, and both are part of the permanent collection. The Tetra 27 duo is EUR 1,660 with a steel back and EUR 1,880 with a sapphire back. The Tetra 27 white is EUR 1,900 with a steel back and EUR 2,120 with sapphire, carrying reference 402 against the duo's 410. More detail is at nomos-glashuette.com.
