The 856 I B is the blue-dial version of the 40mm Sinn 856 S UTC case family: Tegimented steel, Ar-dehumidifying, 80,000 A/m magnetic protection. It ran from early 2018 until roughly 2022, sold exclusively through WatchBuys, Sinn's North American distributor. It never appeared on sinn.de and was never sold in Europe.
Not to be confused with the Sinn 556 I B, which is the 38.5mm sunburst-dial one. Different watch, different case, different finish.
Same watch in both photos. The matte navy dial reads nearly black in shade and turns properly blue in direct light. That shift is the whole point of the watch.
Specs
| Spec | Value |
|---|---|
| Reference | None (see below) |
| Diameter | 40 mm |
| Height | 11 mm |
| Lug-to-lug | 47.5 mm |
| Lug width | 20 mm |
| Weight (no strap) | 70 g |
| Case | Stainless steel, Tegimented, hand-satinised |
| Crystal | Sapphire, AR-coated both sides |
| Caseback | Solid, screwed, steel, not Tegimented |
| Water resistance | 20 bar (200 m) |
| Movement | Sellita SW300-1, 25 jewels, 28,800 vph |
| Power reserve | ~42 hours |
| Functions | Hours, minutes, seconds, date at 4 |
| Antimagnetic | 80,000 A/m (100 mT) |
| Special | Ar-Dehumidifying technology |
| Warranty | 3 years |
1,980 USD on strap / 2,300 USD on bracelet (2020, discontinued)
The limited edition that wasn't
Every listing calls this a limited edition. It was not one, and the evidence is fairly clear:
- WatchBuys listed it as "limited production", never "Limited Edition". Their actual limited editions carried the words explicitly in the product name (856 B-Uhr Limited Edition, 158 Bundeswehr Limited Edition).
- No production count was ever published, by anyone.
- The caseback has no limitation numbering.
- It came back in stock in November 2021, years after launch. Numbered editions do not restock.
The caseback reads Sinn 856.9798. That is a serial, not a reference: Sinn engraves {model}.{unit number}, so this was the 9,798th 856 built. There is no Sinn factory reference for the 856 I B, because "856 I B" is a WatchBuys product name, not a Sinn designation. The standard 856 is ref 856.011. Ignore eBay's catalogue entry claiming "856I" as a reference, it also claims 100m water resistance, which is wrong by half.
There is a genuine blue 856 limited to 50 pieces, sold only in Japan as 856.BLUE. It has Arabic numerals, so it is a sibling of the 856 A, not this watch. That watch is probably where the limited edition story started.
Naming
Sinn's suffixes are literal German:
- I = Indizes, applied baton indices. The alternative is A for Arabic numerals.
- B = Blau.
Background
The 856 I B differs from the standard 856 in two ways beyond the dial. The case is hand-satinised rather than bead-blasted, which gives it a brighter, dressier finish and makes it read less like a pure tool watch. And the dial is matte, not the glossy dial of the 856 I or the sunburst of the 556 I B. Everything else is stock 856: same movement, same shielding, same 200m.
The magnetic protection comes from a soft iron inner case, which is why the caseback is solid. The Ar-dehumidifying capsule (copper sulphate, visible in the lug) keeps moisture out and pushes the service interval to roughly 7-8 years, against 4-5 for the 556 which lacks it.
Robert Farago reviewed it for The Truth About Watches in September 2020 and gave it 5/5, calling it "the world's most legible timepiece". His sample ran at -1 s/day. His spec block lists an ETA 2824, which contradicts his own body text and every other source. It is a mistake, inherited from 556 I B listings. The movement is the SW300-1, the 2892-A2 clone, which is why the watch is 11mm thick rather than 13.
Buying today
Discontinued and never sold in Europe, so this is a US secondary-market watch. Prices have moved:
| Date | Price | Note |
|---|---|---|
| Nov 2018 | $1,500 ask | On strap |
| Dec 2021 | $1,410 sold | OEM strap and box |
| Jul 2026 | ~$1,950 | On bracelet, full kit |
Chrono24 currently has no blue-dial 856 listings at all. WatchUSeek's sales corner and Topper Fine Jewelers are the realistic sources. Expect to import to Germany and pay 19% EUSt on top.
Worth knowing before buying:
- Buy on the bracelet if you can. The satinised Tegimented bracelet suits the satinised case and cost $320 extra new, more than that to add later.
- The dial reads black indoors. If you want obvious blue, the 556 I B sunburst is the more colourful watch, and it is still in production at €1,350.
- 47.5mm lug-to-lug on a 40mm case wears compact. Fine on a 6.75" wrist per owners.
My take
The interesting part is not the blue, it is the satinised case. It softens the 856 into something wearable with a jacket while keeping every bit of the tool-watch engineering underneath. My 856 S UTC is bead-blasted and reads purely functional; this one does not.
The scarcity is real but accidental: no one made it rare on purpose, WatchBuys just stopped ordering it. That is a better reason for a watch to be uncommon than a number on a caseback. At around $1,950 imported it is not a bargain against a new 856 at €2,290, so it only makes sense if you specifically want the matte blue and the satin finish.
Links
The TTAW review is the only in-depth one. The live URL currently throws a 500, so use the archive:
