Omega 670

The Omega 670 powered some of the most elegant mid-century dress watches Omega ever produced, serving as the automatic heartbeat of the Seamaster De Ville during a decade when refined taste met serious horological competence. At 17.5mm diameter and just 4.3mm tall, the 670 delivered full-rotor bi-directional automatic winding in a package thin enough for mid-size cases measuring 31 to 32mm, a format that dominated dressy 1960s wristwear. The movement sits firmly in Omega’s second-tier production grade: robust, well-engineered, non-chronometer, designed for reliable daily service rather than observatory competition.​

The caliber 670 belongs to a carefully structured movement family that Omega developed in the early 1960s to serve dress watch production across manual-wind and automatic configurations. The manual-wind caliber 620 established the architecture at 19,800 vph with hours and minutes only, the 630 added sweep seconds to the 620 platform, and the 670 introduced bi-directional automatic winding to the 630’s three-hand layout. All four calibers (620, 625, 630, 635, and their automatic counterparts 670, 671, 680 series) share the same 17.5mm diameter and critical mechanical components, creating a parts ecosystem that remains advantageous for service and restoration sixty years later.​

Production volume for the caliber 670 is not manufacturer-confirmed, but serial number analysis and case reference cross-checks suggest Omega produced several hundred thousand units during the ten-year run from 1961 to 1971. Watches with caliber 670 typically carry serial numbers from 18,000,000 (1961) through approximately 31,000,000 (early 1971), providing a rough production window that corresponds to Omega’s aggressive mid-size automatic offerings during the peak years of mechanical watchmaking before the quartz crisis. The caliber 670 should be classified as common rather than scarce. Parts availability remains excellent through both genuine Omega channels and aftermarket suppliers, and donor movements from less desirable case configurations provide a deep pool for restoration work.​

Collector demand for caliber 670-powered watches sits in the affordable vintage Omega category. The Seamaster De Ville references that house the 670 represent entry-level access to 1960s Omega quality, trading at significantly lower prices than Speedmaster or professional Seamaster dive watches from the same era. Market values for steel mid-size examples in good condition range from $800 to $1,500, with solid gold US-market variants commanding $1,500 to $3,000 depending on case condition and dial originality. Collector interest centers on dial condition, case integrity, and correct Omega-signed components rather than movement elaboration, since the 670 carries no chronometer certification or special finishing. Demand remains stable but not rising dramatically, prices do not reflect scarcity premium, and the 670 is best understood as a quality daily-wear movement rather than an investment-grade caliber.​

Historical Context, Provenance, and Manufacturing Details

Omega introduced the caliber 670 in 1961 as the logical automatic extension of the manual-wind 620/630 family, addressing a specific market need for thin automatic movements suitable for mid-size dress watches. By 1960, the full-rotor automatic wristwatch had matured technically, and Omega possessed deep experience with bi-directional winding systems developed for the earlier 500 series (calibers 550, 551, 552, and related variants). The 670 applied that winding technology to the newer, thinner 620 platform, delivering automatic convenience in cases previously restricted to manual-wind calibers.​

The caliber 670 evolved directly from the manual-wind caliber 630, which itself descended from the caliber 620 introduced in 1960. The 620 established the 7.75-ligne platform as a two-hand movement (hours and minutes only), the 630 added an indirect sweep seconds mechanism to create a three-hand configuration, and the 670 layered a bi-directional automatic winding system onto the 630’s architecture. This developmental progression followed Omega’s systematic approach to movement families: establish a base manual-wind caliber, add complications or functions incrementally, and maintain dimensional compatibility to maximize case design flexibility and parts interchangeability.​

The caliber 670 was eventually succeeded by movements in the 1000 series as Omega transitioned to higher-frequency calibers and consolidated production in response to the quartz crisis. By the early 1970s, the industry standard frequency had shifted from 19,800 vph to 21,600 vph and eventually 28,800 vph, driven by improved materials and manufacturing precision. Omega introduced the caliber 625 in 1973 as a 21,600 vph replacement for the 620, representing the same frequency evolution that would eventually render the 670’s 19,800 vph beat rate obsolete. Production of the 670 ended in 1971, and by the mid-1970s, Omega had largely abandoned this size class of automatic movement as quartz technology began dominating the dress watch segment.​

The caliber 670 is an in-house Omega manufacture movement, designed, produced, and finished entirely within Omega’s facilities in Bienne, Switzerland. This distinguishes the 670 from ebauche-based calibers that other manufacturers sourced from movement suppliers like ETA, AS (Adolf Schild), or Peseux. Omega maintained vertical integration for its core movement families during the 1960s, controlling everything from component fabrication through final regulation. The 670’s architecture, gear ratios, automatic winding mechanism, and finishing specifications are unique to Omega and reflect the brand’s mid-grade production standards for non-chronometer dress watches.​

Manufacturing remained concentrated in Omega’s Bienne facility throughout the caliber 670’s production run from 1961 to 1971. No evidence suggests production shifts or satellite manufacturing locations during this period. The movement’s design represents mature 1960s Swiss watchmaking: proven Swiss lever escapement, Glucydur balance wheel for temperature compensation, Nivarox hairspring for magnetic resistance and stability, and Incabloc shock protection. The 670 was not groundbreaking but rather represented solid execution of established technology, prioritizing reliability and manufacturability over technical innovation. In the broader context of horological history, the 670 occupies the workhorse category—a competent, well-made caliber that served its intended purpose without pushing technical boundaries.​

Construction and Architecture

The caliber 670 employs a traditional three-quarter plate construction with separate bridges for the train wheels, balance cock, and automatic winding mechanism. The main plate is brass, chosen for machinability and stability, with a functional perlage finish on visible surfaces to trap dust particles and provide a neat appearance. The movement does not feature luxury finishing techniques like Côtes de Genève or hand-beveled anglage on the bridges, appropriate for a non-chronometer, second-tier production grade. The automatic winding mechanism mounts on the dial side of the main plate, with the rotor bridge securing the oscillating weight via a central bearing and gib system.​

The balance wheel is a smooth-rim Glucydur design, manufactured from beryllium bronze alloy for dimensional stability across temperature variations. Glucydur’s high thermal expansion coefficient works in conjunction with the Nivarox hairspring to create a temperature-compensated oscillating system that maintains consistent rate between 5°C and 35°C without requiring a bimetallic compensating balance. The balance diameter measures approximately 10-11mm based on the 7.75-ligne movement size, and the smooth rim design eliminates adjustable timing screws, meaning dynamic poising occurs during manufacture through material removal rather than addable weights. This simplified construction reduces manufacturing complexity and eliminates a common service failure point (loose or lost timing screws), though it limits the watchmaker’s ability to correct poising errors during service without specialized equipment.​

The hairspring is a flat Nivarox spiral, the Swiss industry standard alloy containing iron, nickel, chromium, titanium, and beryllium. Nivarox provides excellent elastic properties, minimal magnetic susceptibility, and strong resistance to temperature-induced rate variation. The hairspring terminates at a standard collet friction-fitted to the balance staff at the inner end, with the outer terminal passing through the two pins of an index regulator for rate adjustment. The spring does not feature a Breguet overcoil or special terminal curve, consistent with the movement’s non-chronometer grade. The hairspring’s active length determines oscillation frequency, and the regulator pins allow the watchmaker to lengthen (retard) or shorten (advance) the effective spring length to adjust the daily rate.​

The escapement is a Swiss lever design, the industry-standard mechanism for mechanical wristwatches since the 18th century. The escape wheel has 15 teeth (typical for Swiss lever escapements operating at 19,800 vph), and the pallet fork carries two synthetic ruby pallet stones set at precise angles to provide appropriate draw, lock, and impulse. The escapement operates at a lift angle of 48 degrees, meaning the balance wheel rotates 48 degrees of arc during each impulse from the escape wheel. This conservative lift angle balances energy efficiency against adequate impulse force, typical for vintage Swiss movements of this grade.​​

Shock protection employs the Incabloc system, the most common Swiss shock protection device of the 1960s. Incabloc protects the balance staff pivots (the thinnest and most vulnerable components in the movement) through spring-mounted jewel settings that can deflect during impact and return to center position. The system uses characteristic lyre-shaped springs visible on both the balance cock (upper pivot) and the main plate (lower pivot), providing protection against axial and lateral shocks. The caliber 670 does not feature shock protection on the pallet fork pivots, typical for movements of this grade.​

Rate regulation employs a traditional index regulator mounted on the balance cock. The regulator consists of a movable arm with two pins that embrace the hairspring’s outer coil, a numbered scale indicating rate adjustment direction, and a fine adjustment mechanism. To increase rate (make the watch run faster), the watchmaker moves the regulator toward the “+” or “A” (Avance/Advance) marking, effectively shortening the hairspring’s active length. To decrease rate (make the watch run slower), the regulator moves toward the “-” or “R” (Retard) marking, lengthening the active length. This system allows precise rate adjustment but requires periodic service as the regulator can shift position during shocks or vibration.​

The mainspring is a Nivaflex white alloy spring measuring 0.95mm height, 0.078mm thickness, 180mm length (some sources indicate 240mm), with an outer diameter of 6.50mm when coiled in the barrel. The spring features a slipping bridle at the outer attachment point, allowing the spring to slip when fully wound to prevent overwinding damage when the rotor continues to wind the movement beyond full power. The mainspring is contained within a barrel with arbor (part 1200), and the barrel arbor (part 1204) can be serviced separately if the square hole wears.​

The gear train follows a conventional four-wheel layout: barrel, center wheel (with attached cannon pinion), third wheel, and fourth wheel. The center wheel is driven directly by the barrel and rotates once per hour, carrying the minute hand via the friction-fit cannon pinion. The third wheel meshes with the center wheel pinion and drives the fourth wheel. The fourth wheel carries the sweep seconds hand and drives the escape wheel at the required ratio to achieve 19,800 vibrations per hour. The center wheel features jeweled upper and lower pivots in the caliber 670, a notable upgrade from the manual-wind 620 which uses bushings for the center wheel. This jeweling improves performance and reduces wear.​​

The automatic winding mechanism employs a full-rotor bi-directional system, representing mature automatic technology for the 1960s. The rotor (part 1026) is a weighted half-moon mass that rotates 360 degrees on a central bearing, with a gib (part 1451) securing it to the rotor bridge (part 1043). Both clockwise and counterclockwise rotation of the rotor wind the mainspring through a reversing gear system that converts bidirectional motion into unidirectional winding of the barrel. The winding gear comprises two winding wheels with satellite pinions that engage depending on rotor direction, transmitting rotational force to the automatic ratchet wheel which drives the mainspring barrel.​

Finishing quality on the caliber 670 is functional rather than decorative, appropriate for a non-chronometer, second-tier production movement. Visible surfaces receive perlage (circular graining) to create a neat appearance and trap dust particles, but the movement does not feature Côtes de Genève (Geneva stripes), hand-beveled anglage on bridge edges, or polished screw heads. The level of finishing is consistent with Omega’s standard production grade, superior to basic ebauche movements but well below chronometer or observatory-grade calibers. Component manufacturing quality is high with precise tolerances and good material selection, but decorative finishing remains minimal.​

Cross-Reference Data

Alternative Caliber Names and Elaborated Versions

The difference between the 17-jewel caliber 670 and the 24-jewel caliber 671 lies in additional jeweling of the automatic winding mechanism and potentially the center wheel’s upper pivot. The base timekeeping train (escapement, balance, and wheel pivots) remains identical between the two versions, meaning performance differences are minimal. The extra seven jewels in the 671 primarily improve longevity of the automatic winding components rather than enhancing chronometric performance.​

Compatible Case References by Brand

US-market references (prefix “B” or “KL/LL/KM”) were cased by American manufacturers including Jonell and Ross Watch Case Corporation. These cases feature different proportions from Swiss-market references, typically with thinner lugs and different crystal profiles. All US-market cases with caliber 670 used only the 17-jewel version, while Swiss-market cases could house either caliber 670 or the higher-grade caliber 671.​

Crown and Stem Specifications

The winding stem (part 1106) is shared across the entire 620/625/630/635/670/671/672/680/681/682/683/684/685 family, significantly improving parts availability but requiring careful verification of stem length for specific case designs. The stem length of 12.1mm is a standard specification, but some cases may require shorter stems depending on crown tube depth and case thickness.​

Parts Compatibility and Interchangeability

The caliber 670 shares extensive parts compatibility with related calibers in the 620-685 family:

Shared across 620, 630, 670, 671, 672, 680, 681, 682, 683, 684, 685:

• Pallet fork (part 1316)​
• Regulator (part 1331)​
• Winding stem (part 1106)​
• Various keyless works components (parts 1106, 1107, 1108, 1109, 1110, 1111, 1113)​

Shared across automatic variants (670, 671, 672, 680, 681, 682, 683, 684, 685):

• Rotor gib (part 1451)​
• Escape wheel (part 1305)​
• Balance complete (part 1327)​

This extensive parts sharing creates a large donor pool for restoration and repair, though it also increases the risk of incorrect replacement parts being installed during previous services. Watchmakers must verify correct specifications for jewel count, date mechanism presence, and chronometer adjustments when encountering these movements.​

Identification Marks

Caliber Number Location

The caliber number “670” is engraved on the main plate, typically visible when viewing the movement from the dial side after removing the rotor and automatic mechanism. Some examples show the caliber marking on the train bridge visible from the case back side. The marking is engraved rather than stamped, with serif font typical of 1960s Omega production.​

Logo and Brand Marks

Authentic caliber 670 movements display the Omega symbol (Ω) prominently on the rotor, typically in a polished or relief finish. The main plate may also carry the Omega logo engraved near the balance cock or on the winding mechanism bridges. The movement should not display any other brand markings, as the 670 was manufactured exclusively for Omega watches and never sold as an ebauche to other brands.​

Date Codes and Serial Numbers

Omega movements from the 1960s use a seven-digit serial number stamped on the movement, typically visible on the main plate near the balance cock or on the automatic mechanism bridge. The serial number dates the movement production according to Omega’s sequential numbering system:

• 18,000,000 to 18,999,999: 1961
• 19,000,000 to 19,999,999: 1962
• 20,000,000 to 21,999,999: 1963
• 22,000,000 to 22,999,999: 1964-1965
• 23,000,000 to 24,999,999: 1966-1967
• 25,000,000 to 27,999,999: 1967-1969
• 28,000,000 to 31,999,999: 1969-1972​

The caliber 670 was produced from 1961 to 1971, so legitimate examples should carry serial numbers between approximately 18,000,000 and 31,000,000. Serial numbers outside this range indicate either a different caliber or a mismatched movement.​

Finishing Marks and Expected Characteristics

The caliber 670 displays functional finishing appropriate for its production grade:

Perlage (circular graining): Visible on the main plate and some bridges, particularly on surfaces visible through the case back. The perlage should be regular and uniform, though not as fine as high-grade movements. The pattern helps trap dust and provides visual interest.​

No Côtes de Genève: The caliber 670 does not feature Geneva stripes on the bridges, a decorative finish reserved for higher grades. Presence of Côtes de Genève would indicate either extensive refinishing or a misidentified movement.​

No hand-beveled anglage: Bridge edges are chamfered but not hand-polished to a mirror finish. The edges show machine chamfering consistent with production-grade movements.​

Screw heads: Standard slotted steel screws without bluing or polishing. The screws are functional rather than decorative.​

Jewel Settings

The 17 jewels in the caliber 670 are set in standard brass settings without gold chatons. The jewels are synthetic rubies, standard for Swiss watchmaking of this era. The jewel count should be verified against the stated specification, as some movements may have had jewels added or removed during incorrect servicing. Correct jewel placement for a 17-jewel movement includes:

• Balance staff upper and lower pivots: 2 jewels (with cap jewels making 4 total)
• Pallet fork pivots: 2 jewels
• Escape wheel pivots: 2 jewels
• Fourth wheel pivots: 2 jewels
• Third wheel pivots: 2 jewels
• Center wheel pivots: 2 jewels (upgrade from 620 which used bushings)
• Rotor bearing: 1 jewel​​

Adjustment Markings

The caliber 670 is not chronometer-rated and should not carry chronometer adjustment markings. Authentic examples should not display markings indicating “Adjusted to 5 Positions and Temperature” or similar chronometer-grade specifications. If such markings appear, they likely indicate transplanted components from a caliber 551 or other chronometer-grade movement, as documented in serviced examples where automatic mechanism bridges were swapped during repair.​

Expected Engravings and Stampings

Legitimate caliber 670 movements should display:

• Caliber number “670” engraved in serif font
• Seven-digit serial number
• Omega symbol (Ω)
• Jewel count “17 JEWELS” or “17 RUBIS”
• “SWISS” or “SWISS MADE”
• Height indicator (H1, H2, or H3) inside the Omega logo, denoting dial clearance for different crystal profiles​

The engravings should show consistent depth and clarity appropriate for factory markings. Crude, shallow, or inconsistently styled engravings may indicate refinished plates or counterfeit components.​

Font and Marking Style by Production Era

Omega maintained relatively consistent engraving styles throughout the caliber 670’s production from 1961 to 1971. The font is a refined serif style typical of Swiss watchmaking, with clear, crisp lines and appropriate depth. Earlier examples (1961-1965) may show slightly different rotor decoration than later examples (1966-1971), but core movement markings remained consistent.​

Part Information

Key Component Part Numbers

Sourcing Notes

Parts availability for the caliber 670 remains excellent as of 2026. Genuine Omega parts are available through authorized service centers and specialist suppliers including Perrin Watch Parts, Watch Material, Gleave & Co., Ofrei, and Cousins UK. Generic replacement parts of acceptable quality are available for wear items including mainsprings, stems, and gaskets.​

Commonly available components:

• Mainsprings (both genuine Omega and high-quality generic Nivaflex)
• Winding stems (genuine and generic)
• Balance complete assemblies (used, good condition)
• Pallet forks (genuine)
• Escape wheels (genuine)
• Barrels with arbors (genuine)
• Regulators (genuine)
• Case clamps (genuine)
• Rotors and rotor bridges (used, good condition)

Harder to source components:

• Dial-side automatic mechanism parts (winding gears, intermediate wheels)
• Specific cannon pinion heights
• Damaged or worn main plates (movement must be replaced entirely)

Parts that commonly fail:

• Mainspring (loses tension with age, typically requires replacement during service)
• Yoke/clutch lever spring (part 1112 or similar, weakens over time, causes poor hand-setting feel)​​
• Rotor bearing (wears with extended use, causes noisy rotor or poor winding efficiency)
• Center wheel bushing or jewel (wear point, though less common with jeweled version)

Acceptable generic replacements:

• Mainsprings: Swiss-made Nivaflex generic springs of correct dimensions perform equivalently to genuine Omega springs
• Crystals: Generic acrylic or mineral crystals of correct diameter fit period-correct cases
• Gaskets: Generic case back gaskets of correct size provide adequate sealing
• Stems: Generic Swiss-made stems with TAP 10 thread work correctly, though length verification is critical

Service parts availability will continue for the caliber 670 given the large production volume, extensive donor movement pool from less desirable cases, and ongoing collector interest in 1960s Omega dress watches.​

Performance Data

Manufacturer Specifications

Omega specified the following performance parameters for the caliber 670 when new:

Accuracy: Not chronometer-rated, no specific accuracy specification published. Typical expectations for non-chronometer Swiss movements of this grade: +/- 20-30 seconds per day when new and properly regulated.​

Positions tested: Not specified. The caliber 670 is an unadjusted movement, meaning it was not tested or regulated in multiple positions. Factory regulation occurred in a single position (typically dial up), suitable for a non-chronometer dress watch movement.​

Temperature compensation: Yes, inherent in the Glucydur balance and Nivarox hairspring combination. The system maintains relatively stable rate between 5°C and 35°C (41°F to 95°F), the typical temperature range for wrist-worn watches.​

Isochronism: Not specified. Isochronism (consistent rate regardless of mainspring power level) improves with proper mainspring selection and escapement adjustment, but the caliber 670 was not specifically tested or optimized for isochronic performance.​​

Observed Performance (Field Data)

Based on collector reports, watchmaker observations, auction house timing results, and forum discussions of serviced examples, typical performance for well-maintained caliber 670 movements:

Accuracy range for well-maintained examples:

• Dial up (horizontal): +5 to +15 seconds per day
• Crown down (horizontal): +3 to +12 seconds per day
• Vertical positions: -5 to +20 seconds per day
• Expected variation between positions: 10-20 seconds per day
• Overall daily average with mixed wearing: +/- 10-15 seconds per day​

These figures assume recent service (within 3-5 years), proper lubrication, clean components, and correct regulation. The caliber 670 was never chronometer-grade, so expectations should align with standard Swiss production movements rather than observatory pieces.

Expected amplitude:

• Dial up, fully wound: 270-290 degrees
• Dial up, after 24 hours: 240-260 degrees
• Vertical positions (crown down, crown up, crown left, crown right): 220-250 degrees
• Minimum acceptable amplitude: 200 degrees (below this indicates service needs)​​

Amplitude drops of 20-30 degrees from horizontal to vertical positions are normal and expected. Amplitude drops of more than 40 degrees suggest problems with mainspring power, escapement efficiency, or excessive friction.​​

Beat error:

• Target: 0.2-0.5 milliseconds
• Acceptable: 0.5-0.8 milliseconds
• Poor/needs adjustment: Above 0.8 milliseconds​​

Beat error above 1.0 milliseconds indicates improper balance staff positioning, damaged hairspring, or incorrect service work and requires correction.​

Common performance issues and causes:

• Low amplitude (below 220 degrees): Weak or damaged mainspring, dirty or incorrectly lubricated escapement, dried or incorrect oils on jewels, damaged balance pivots, excessive magnetization
• Erratic rate: Damaged hairspring (bent coils, incorrect flat position), magnetized balance or hairspring, loose or damaged jewel settings, damaged escape wheel teeth
• Positional variation exceeding 30 seconds per day: Balance wheel poising errors, damaged pivots, bent balance staff, hairspring terminal curve touching index pins
• Stopping or intermittent running: Weak mainspring, excessive friction in gear train, damaged escapement, damaged or misaligned automatic mechanism components​

Performance degradation with age:
As the movement ages without service, typical degradation patterns include:

• Gradual decrease in amplitude as lubricants dry, congeal, or migrate (typical timeline: 5-7 years between services)
• Increasing positional variation as pivot holes wear and clearances increase
• Declining power reserve as mainspring loses tensile strength (typical timeline: 10-15 years before mainspring replacement needed)
• Increased rate variation as hairspring accumulates minor deformations or magnetization

Properly serviced every 5-7 years with complete disassembly, cleaning, lubrication, and regulation, the caliber 670 can maintain acceptable performance for decades. The movement benefits from robust construction and good material choices, making it suitable for regular daily wear with appropriate maintenance intervals.