Every watch we make in our Toronto workshop is built around the same heart: the Seiko NH35 automatic movement. Plenty of brands would rather you didn’t look too closely at what’s ticking inside their cases. We’d rather you did — because the NH35 is one of the most quietly impressive pieces of engineering you can put on a wrist, and understanding it makes owning one better.
This is the honest version: what the movement is, where it comes from, what the numbers on the spec sheet actually mean, and why we chose it over the alternatives.
What the NH35 actually is
The NH35 is a mechanical automatic movement made in-house by Seiko Instruments — the same group that builds the calibres inside Seiko’s own watches. When Seiko fits this movement to its own pieces it’s called the 4R35; when it sells the identical movement to other watchmakers, it’s stamped NH35. Same factory, same parts, different engraving.
It arrived in 2011 as the successor to Seiko’s legendary 7S26 — a movement famous for running for decades inside dive watches that were never once serviced, oiled, or treated kindly. The NH35 kept that tank-like architecture and added the two features enthusiasts had been asking for: hacking seconds (the seconds hand stops when you pull the crown, so you can set the time exactly) and hand-winding (you can wind it from the crown instead of shaking it awake).
Today it is, without much argument, the most widely used automatic movement in the world. Independent watchmakers, respected microbrands, and custom houses like ours all build on it — not because it’s cheap, but because it has proven itself in tens of millions of watches.
The numbers that matter
Spec sheets love numbers. Here’s what the NH35’s actually mean on your wrist:
- 21,600 beats per hour (3 Hz). The balance wheel swings six times a second, which is why the seconds hand glides instead of ticking. A slightly relaxed beat rate is also part of why this movement lasts so long — less speed, less wear.
- 24 jewels. These are tiny synthetic rubies used as bearings at friction points. Ruby is harder than steel and nearly frictionless when oiled, so the parts that pivot thousands of times a day ride on jewels instead of grinding metal on metal.
- About 41 hours of power reserve. Fully wound, the watch runs almost two days off the wrist. Take it off Friday evening and it will still be running Sunday morning.
- Bidirectional automatic winding. Seiko’s “Magic Lever” system winds the mainspring whichever way the rotor spins — an elegantly simple pawl mechanism with very few parts to wear out. Normal daily wear keeps the watch fully wound.
- Diashock protection. The balance staff — the most fragile part of any mechanical watch — sits in a sprung setting that absorbs knocks. Dropped-on-the-bathroom-floor insurance, engineered in 1956 and refined ever since.
Accuracy, without the marketing
Seiko’s official tolerance for the NH35 is −20 to +40 seconds per day. Read cold, that sounds loose — and if a watch actually gained 40 seconds a day, it would be. But that figure is the factory’s worst-case promise, not what the movement does.
In practice, a healthy NH35 worn daily usually settles within about ±10 seconds a day, and the movement responds beautifully to regulation. Before any IVERA leaves the workshop, we time it on a machine in multiple positions and adjust the regulator — most of our watches leave running within a few seconds a day. That’s the difference between a movement dropped into a case and a movement finished by a watchmaker.
One habit worth knowing: mechanical movements are sensitive to position overnight. If your watch runs a touch fast, resting it crown-down on the nightstand will often slow it slightly; dial-up tends to do the opposite. Owners have been fine-tuning their watches this way for a century.
Why not a Swiss movement?
Because at this price, the NH35 is genuinely the better watch. A Swiss-made movement of equivalent robustness would double or triple the cost of the finished piece without keeping better time. What you’d be paying for is the word “Swiss” — and we’d rather put that money into the parts you actually see and touch: the dial, the case finishing, the sapphire crystal, the strap.
There’s also the long game. The NH35 is so universal that any competent watchmaker on earth can service it, and parts will be available for decades. A full service costs a fraction of what a boutique Swiss calibre demands — and if the movement is ever damaged beyond economic repair, it can be replaced entirely for less than a Swiss service bill. Your watch is never stranded. That’s what lets us honestly call a $500 watch an heirloom: it can be kept running forever, affordably.
Living with one
An automatic watch asks for a little ritual, and gives a lot back. If yours has stopped, twenty slow turns of the crown gets the mainspring started, then wear it — the rotor does the rest. Set the time with the crown fully out, push it home, and you’re done.
Two small courtesies will keep it happy for years. First, avoid changing the date in the late evening hours around midnight, when the calendar gears are already engaged — set the time to the morning first, then adjust the date. Second, keep it a hand’s width away from strong magnets (speaker grilles, magnetic phone mounts, induction hobs); magnetism is the most common cause of a suddenly fast watch, and also the easiest to fix.
Service it every five to seven years, or honestly — whenever it starts drifting. It will outlast the person who bought it. That’s rather the point.
Choose what surrounds it
Every watch in our collection carries this movement, regulated by hand. If you’d rather decide every visible part yourself — case, dial, strap, engraving — the builder will render your watch live as you design it.