Omega Seamaster Diver 300M Co-Axial 42mm Mens Watch Blue
10 % below RRP
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ℹ️ 1-month trend
Price change over the past 30 days. Shows the short-term market movement — relevant if you want to buy or sell soon.
ℹ️ 4-month trend
The central metric behind the momentum score. It filters out short-term swings and shows the true, medium-term market trend of this reference.
ℹ️ Volatility
Annualised price fluctuation. Below 10 % = very stable, 10–20 % = normal, above 20 % = volatile. With high volatility the price can change quickly — in both directions. Be cautious about buying without checking the current price.
ℹ️ Momentum score
ChronoCheck's own indicator from 0 to 100, calculated from the 4-month trend, volatility and market direction.
- Above 60 — Upward trend. Good time to sell, prices are rising.
- 40 – 60 — Neutral. Stable price level, no pressure to act.
- Below 40 — Downward trend. Wait or enter at a good price.
ℹ️ Investment Grade A/B/C/D
ChronoCheck's own rating for each reference. A 0–100 point scale, made up of four weighted components:
- Momentum (40 pts) — trend strength from the momentum score.
- Liquidity (25 pts) — number of active live listings.
- Stability (20 pts) — inverse volatility — the calmer, the better.
- Source robustness (15 pts) — number of independent market sources.
- A · 75+ Trend is right, liquidity good, data broad.
- B · 55–74 Solid, but one component weaker.
- C · 35–54 Average, volatility or market breadth weigh on it.
- D · below 35 Downward or too little data — a collector's piece.
Not investment advice. Pure data analysis from aggregated market sources.
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Technical data
Omega Ref. O21020422003002 — Variants and collector names
Known as: Two-Tone 300M, Bicolor Seamaster, Sedna Diver, SM300 Bicolor Blue
Movement variants
- 8800 (2018–today) · 25200 bph
Bezel variants
- SD300M-42-Blau-Keramik-Ceragold-Sedna-60min
Dial variants
- SD300M-42-Blau-Keramik-Wellen-Sedna-Date — OMEGA / SEAMASTER / DIVER 300M / CO‑AXIAL MASTER CHRONOMETER / date at 6 o'clock; laser-engraved wave pattern; applied 18K Sedna Gold indices with white SLN
Crystal variants
- Saphir-gewoelbt-AR-SM300M-42
Bracelet variants
- Seamaster Diver 300M Stahl / Sedna Gold Armband Ref. SD300M-42-3Link-StahlSedna-2018
The Omega Seamaster Diver 300M O21020422003002 is one of the few dive watches that trades on the secondary market under two names: "Two-Tone 300M" or "Sedna Diver" — depending on which generation the buyer has in mind. Both refer to the same 42mm steel case with Sedna Gold accents, which Omega pairs with a blue ceramic dial featuring a wave pattern. The date sits at 6 o'clock, and the blue ceramic bezel with Ceragold numbering carries a 60-minute scale.
## The Heart of the Matter: Calibre 8800
Powered by Omega's in-house Calibre 8800, this reference is one of the most technically accomplished pieces in the current Seamaster lineup. The movement is Master Chronometer-certified, resists magnetic fields up to 15,000 gauss, and delivers a 55-hour power reserve. What that means in practice: set it down on a Friday evening, and it's still running Monday morning. For a steel-and-gold watch with a list price well above $11,662 none of that is a given.
## Why the Two-Tone Market Plays by Its Own Rules
The secondary market for two-tone Seamaster variants behaves differently from its all-steel counterparts. Buyers actively seek out the Sedna tone because Omega deliberately kept the gold-to-steel ratio restrained — this is not a gold-plated watch, but one with 18-karat rose gold on the crown, bezel housing, and bracelet center links. Price movements here track the gold market more closely than the broader Omega secondary market.
Brand profile: Omega
Omega is the second most counterfeited Swiss watch brand. The Speedmaster and Seamaster are especially targeted. Pay close attention to movement details (Co-Axial) and dial textures.
- Speedmaster: The chronograph reset hand must snap back precisely to 12 o'clock — fakes stop 1–3 seconds off or wobble
- Speedmaster (Hesalite): The Omega logo is micro-laser-etched on the UNDERSIDE of the Hesalite crystal — only visible at a specific angle and in the right light — fakes omit it or place it incorrectly
- Seamaster: The wave-pattern dial must be ENGRAVED (tactile relief) — printed/flat wave lines = fake
- DON (Dot Over Ninety): small dot ABOVE the '90' on the Speedmaster tachymeter bezel — position/size often wrong on fakes
Serial number format: Omega serial number: 8-digit number on the caseback or between the lugs (on older models). Since ~2018 engraved on the caseback at 6 o'clock. Format: purely numeric. Verifiable on the Omega website with an extract from the archive.
Further sources
Buying guide: Omega Seamaster Diver 300M Co-Axial 42mm Mens Watch Blue
Market situation and price range
At $14,975 the Seamaster Diver 300M Co-Axial 42mm Mens Watch Blue sits in a segment where first owners sell regularly — clean pieces with box and papers are not uncommon. The jump from "good" to "very good" usually costs 1,000 to 2,000 euros more at purchase. You get that premium back on resale if the condition is preserved.
What to look out for when buying?
- Authenticity: The serial number and reference on the case must match the papers. A professional authenticity check of the Omega Seamaster Diver 300M Co-Axial 42mm Mens Watch Blue reliably rules out counterfeits.
- Condition: Check scratches on the case and bezel — professional refurbishment can leave traces.
- Service history: A documented service by the manufacturer or a certified watchmaker increases the value.
- Scope of delivery: Box, papers and warranty card make a noticeable price difference on the Seamaster Diver 300M Co-Axial 42mm Mens Watch Blue.
- Independent certification: The CPS-52 standard covers 52 checkpoints — from the serial number and the timing machine to water resistance. The result is secured on the blockchain and can be verified at any time.
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