THB Factory works the smaller Rolex Datejust sizes that most workshops ignore. Here is what it builds, why the 31mm is hard, and who it competes with.
Last checked: September 2026
The niche nobody else wanted
THB occupies a corner of this market that exists because of a simple commercial fact: almost every replica workshop builds 40mm and 41mm watches, because that is where the photographs and the forum attention are. Demand for smaller cases is real and steady, and supply is thin.
THB builds the 31mm Rolex Datejust. That is the whole proposition, and in a trade full of workshops claiming everything it is a refreshing amount of honesty about scope.
Why a smaller case is harder, not easier
The intuition is that a smaller watch is a simpler watch. It is the opposite.
A case cannot simply be scaled down. The movement inside has to fit a reduced diameter, which means either a genuinely smaller calibre or an ugly spacer ring that shows through the caseback. The date mechanism has to reach the window at a different geometry. The bracelet has to taper from a narrower lug width without the links looking stubby, and the clasp has to shrink without losing the click.
Get any of it wrong and the watch reads as a large watch that shrank, which is exactly how most attempts at small cases in this market look.
What THB gets right
Proportion, mainly. The lug to bracelet transition and the bezel to dial ratio on a THB 31mm read as a watch designed at that size rather than reduced to it. On a small watch that is most of the battle, because there is less dial to distract from a wrong outline.
The fluted bezel work is competent. Not the sharpest in this market, and better than anything else available at 31mm.
Where it sits
THB is a mid tier workshop and it is not pretending otherwise. On movement finishing and case machining the top Datejust specialists are ahead, and the reason to look at THB is that they largely do not build this size.
ARF is the exception and does build a 31mm, which makes it the direct comparison. ARF is the stronger workshop overall. THB is worth asking about when a particular reference or dial is not available from ARF, which at this size happens often.
Who a 31mm actually suits
Anyone with a wrist under about 16cm, which is a large share of buyers and a group this market serves badly. A 41mm Datejust on a small wrist overhangs the bone and reads as borrowed. The same reference at 31mm reads as fitted.
Our Datejust range carries the dial variants that work at this size, including the Roman and mother of pearl dials that are more common in the smaller cases than the larger ones.
Checks before buying at this size
- Ask for a wrist shot, not a stand shot. Proportion is the whole question at 31mm and a product photograph on white hides it completely.
- Ask about the caseback. A spacer ring around a movement that is too big for the case is the standard shortcut.
- Ask for the lug width. It should be proportionate to the case. A wide lug on a small case is the tell that a larger design was reduced.
Frequently asked questions
What does THB Factory make?
Small case Rolex Datejust references, principally the 31mm. It does not chase the sports models.
Is THB a super clone factory?
No. THB is a competent mid tier workshop. Its value is that it serves a size almost nobody else builds rather than that it leads on movement work.
Why do so few factories make 31mm watches?
Because a smaller case is more work, not less. The movement, the date mechanism, the bracelet taper and the clasp all have to be reworked rather than scaled.
THB or ARF for a 31mm Datejust?
ARF is the stronger workshop where it builds the reference you want. THB is worth asking about when the dial or configuration you want is not available from ARF, which at this size is common.
Where can I see them?
The Datejust collection carries the smaller case references and dial variants.
