Name: Tudor Black Bay 58 925 (Sterling Silver) M79010SG-0001
Brand: Tudor
SKU: M79010SG-0001

Tudor built the Black Bay 58 925 around a premise most dive watch buyers never consider: what if the case aged like silver jewelry, not like steel? The 39mm sterling silver case develops a living patina over time, darkening at wear points in a way no stainless steel watch ever will. If you want a BB58 that looks different from every other BB58 in the room, this is the only one that gets there by design.

What it is

Tudor introduced the Black Bay 58 925 in 2021 as a limited-production variant of its most popular modern reference. The 925 designation refers to sterling silver, an alloy of 92.5% silver and 7.5% copper, which is softer than steel and far less common in dive watches because of its maintenance demands. Tudor paired it with the MT5400, their in-house automatic developed in collaboration with Breitling, giving the watch a movement with genuine manufacture credentials rather than an outsourced base caliber.

The choice of 39mm fits the original BB58 brief of channeling Tudor's 1958 diving references, before dive watches grew to 40mm and beyond as a default. Production numbers have never been officially disclosed, but availability has remained genuinely constrained compared to the standard steel BB58 lineup.

Buying notes

Sterling silver scratches and dents more readily than steel, so buyers who keep watches pristine will find maintenance frustrating. The patina that develops at lugs, crown, and case flanks is the point for some owners and a dealbreaker for others; there is no neutral position. Finding a pre-owned example with patina that you actually like rather than one that looks neglected requires seeing the watch in person or trusting detailed photos.

Tudor does not offer a lacquered or coated version, so if you want to slow the oxidation you are on your own with silver polishing cloths and storage choices. Because production is limited, the secondary market carries a premium over retail and condition ranges vary widely.

Market read

The BB58 925 trades above its retail price on the secondary market, though nowhere near the multiples seen on hotter sport references. Expect to pay a modest premium for unworn examples; polished or heavily patinated pieces move at a discount that reflects individual taste as much as condition. This is not a watch that has historically been flipped for significant profit, which means the buyers holding them tend to actually want them.

Service expectations

The MT5400 is a Tudor in-house automatic rated to 70 hours of power reserve, with a free-sprung balance and chronometer-level accuracy specifications. Tudor service centers handle the movement without issue, and the in-house nature means parts availability is not dependent on third-party suppliers. The silver case requires separate attention during service: a competent watchmaker will clean and lightly address the case, but aggressive polishing defeats the purpose of owning a 925 watch.

Editorial copy is AI-drafted from primary sources and reviewed by Grail Atlas before publication. Where the text is uncertain about a fact, it says so. Email corrections@grailatlas.com if something reads wrong. Signals on this page (community, OSINT) are clearly separated from the editorial sections.

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Movement tier: unclassified · caliber Tudor MT5400: in-house automatic, 28,800bph, 70h PR, 26j; COSC-certified, free-sprung balance, silicon hairspring · 70h power reserve (2.9 days)

Versatile size: fits most wrists (6–7.5 in / 15–19 cm)

39 mm case. The sweet spot for the broadest range of wrist sizes. Neither too dainty nor too bold.

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Authentication

The 925 sterling silver hallmark on caseback and clasp is the primary material verification; no hallmark means a non-genuine case or clasp.

Known issues in the market

The 925 hallmark must appear on both the caseback and bracelet clasp; single-location hallmarks indicate a component replacement.
Polished silver loses its intended toned patina; a bright polished BB58 925 has lost its designed surface character.
Cal. MT5400 is METAS-certified; service must go through Tudor or authorized centers to maintain certification.

Area	What to check	What is correct	Red flag
caseback	925 sterling silver hallmark	925 hallmark clearly struck on the caseback alongside Tudor engravings	No hallmark or a partial/blurred hallmark indicating a non-silver or replacement caseback
bracelet	925 hallmark on clasp	925 hallmark present on the bracelet clasp, consistent with caseback hallmark	Clasp without hallmark indicating a non-silver replacement clasp or bracelet
case	Silver toning and patina	Warm silver toning with tonal variation consistent with the watch age and wear; not uniformly bright	Uniformly bright polished silver surface indicating polishing that removed the natural patina

Common legitimate replacements

Cal. MT5400 is an in-house Tudor movement; service at non-authorized centers may void METAS certification.
Sterling silver bracelets are sometimes replaced with stainless steel bracelets; verify bracelet material matches the 925 spec.

Expert resources: Tudor Black Bay 58 925 documentation at tudorwatch.com. WatchUSeek Tudor subforum for silver hallmark verification and patina assessment.

Authentication guide

Last reviewed June 2026

The BB58 925 is the only Tudor in sterling silver (925 silver purity). The case and bracelet are silver; only the caseback is steel. Silver oxidizes differently than steel, developing a distinctive patina. The "925" designation stamped on the case is the authentication anchor. The MT5400 caliber inside is Tudor's compact in-house movement (no GMT function), and the 39mm case is notably thinner and smaller than the Black Bay 41.

Known reproduction risks

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HIGH RISK

Steel replicas coated or plated to approximate silver appearance.

No "925" purity stamp on the case or bracelet
Case with a uniform metallic sheen across case and caseback (genuine has steel caseback contrasting with silver case)
Weight inconsistent with sterling silver -- silver is denser than aluminum but slightly less dense than steel; the BB58 925 feels different from a steel BB58 due to material density differences
Snowflake hands in wrong proportion for the 39mm case

Dial variants by era

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Era	Description	Identifiers
2021 to present (grey/brown)	Grey-brown dial that picks up the silver case tone. The dial color shifts depending on light; it reads as warm grey or tobacco brown depending on the angle. No date complication.	Grey-brown dial with the silver case tone amplifying the warm color Snowflake hands in the correct proportion for the 39mm case -- narrower than the 41mm BB hands "TUDOR" text at 12 and "BLACK BAY FIFTY-EIGHT" text at 6 in correct typography No date window -- the BB58 and its 925 variant are no-date configurations 925 sterling silver case and bracelet; caseback is steel

Service part flags

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925 silver case and bracelet

Original: Sterling silver (925 parts per thousand pure silver) case and bracelet. The "925" purity mark is stamped on the case and bracelet components. Silver oxidizes to a grey or brownish patina over time; this patina is correct and expected. The caseback is steel, not silver.

Replacement tells

No "925" purity mark stamped on the case midband or bracelet links
Case and bracelet with no patina or oxidation on an example stated to be several years old -- silver that has not developed any oxidation may have been replated or replaced
Steel caseback with no visible distinction from the case material (genuine examples have the steel caseback contrasting with the oxidized silver midcase)
Uniform silver sheen across all components including the caseback -- the caseback should be steel with a different finish than the silver midcase

MT5400 movement

Original: Tudor MT5400 is an in-house automatic, 28,800bph, 70-hour power reserve. METAS-certified. No GMT function. The movement is smaller than the MT5602 family to fit the thinner 39mm case profile.

Replacement tells

Power reserve depleting in under 48 hours from full wind
Crown at position 1 advancing a GMT hand -- the MT5400 has no GMT function
Case thickness inconsistent with the 11.9mm BB58 specification -- a thicker movement in the case would make the watch taller

Snowflake hands (39mm scale)

Original: Snowflake hands scaled to the 39mm case. They are the same profile as the 41mm BB hands but proportionally smaller. The lume plots are rectangular.

Replacement tells

Hands with wrong proportions for the 39mm case -- too wide, too long, or with wrong lume plot shape
Tapered or pointed hand tips rather than the flat snowflake profile

Case back markings

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2021 to present

Steel caseback (not silver) with Tudor shield at center
"TUDOR BLACK BAY FIFTY-EIGHT 925" on the outer ring
"925" purity designation stamped on the case midband
"MANUFACTURE MOVEMENT" and METAS reference
Reference M79010SG and serial number on the case

Movement tells

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MT5400, 28,800bph, 70-hour power reserve. Functionally similar to the MT5602 but without the GMT complication. Fully wound watch should run 65 to 70 hours.
No date complication: crown at position 2 sets the time only. If the crown has a quickset date at position 2, the movement is from a different Tudor reference.
Silicon hairspring: not affected by magnetic fields.

Sources: Fratello -- Tudor Black Bay 58 925 review; Tudor -- BB58 925 specification.