The Omega Constellation 123.55.31.20.55.003 is a 31 mm 18ct white gold dress watch with a diamond-set bezel, a mother-of-pearl dial with diamond indices and the automatic calibre 8521 on a matching white gold bracelet. It sits at the precious-metal, gem-set end of the Constellation family, above the steel and gold quartz 28 mm pieces and alongside the 29 mm gold automatics. This guide covers the specifications, what the Co-Axial Chronometer designation means, how the 31 mm white gold model compares with the smaller quartz and gold-cased Constellations, how it wears, price context in 2026 and what to check before buying. Bizak & Co. sources the 123.55.31.20.55.003 to order; the Omega collection lists the configurations we can seek.
Last reviewed on September 28, 2026 by Filip Biczak. Prices are dated observations, not quotes.
Omega Constellation 123.55.31.20.55.003 specifications
| Attribute | 123.55.31.20.55.003 |
|---|---|
| Case | 31 mm 18ct white gold, about 11.9 mm thick, 19 mm lug width, screw-down crown |
| Bezel | 18ct white gold, diamond-set |
| Movement | Calibre 8521, automatic Co-Axial, 28 jewels, 50 hours power reserve |
| Dial | White mother-of-pearl with diamond-set indices; date at 3 |
| Crystal | Sapphire |
| Bracelet | 18ct white gold, integrated to the case |
| Water resistance | 100 m (330 ft) |
| Family | Omega Constellation Co-Axial Chronometer, precious-metal line |
Source: case, movement and dial data checked against dealer specification pages for this reference at Bezel and Watchfinder on 28 September 2026; both are secondary-market dealers, not the manufacturer, so treat any figures on those pages as retailer disclosures rather than confirmed Omega specifications.
What does Co-Axial Chronometer mean on the Constellation?
The Co-Axial escapement was designed by George Daniels and adopted across Omega's mechanical range from the late 1990s onward. It reduces friction between the escape wheel and pallet compared with a traditional Swiss lever escapement, which Omega uses to justify longer intervals between services. "Chronometer" on the dial refers to a movement that has passed independent timekeeping testing before casing. The Constellation name itself dates to 1952 and has carried Omega's precision claims longer than any other line in the catalogue; the four claws around the bezel and the star at 6 o'clock on the dial are the family's signature details, both present on the 123.55.31.20.55.003.
Omega built the Constellation's early reputation on observatory chronometer trials in the 1950s and 1960s, a period referenced by the star motif rather than spelled out on the dial. The four claws, added when the line was redesigned in the early 1980s, are decorative rather than structural on modern cases, but they remain the visual shorthand that separates a Constellation from Omega's other families at a glance, whether the case underneath is steel, two-tone or, as here, solid white gold.
28 mm quartz, 29 mm gold or 31 mm white gold: choosing a Constellation size
| 28 mm quartz | 29 mm gold automatic | 31 mm white gold (this piece) | |
|---|---|---|---|
| Case | Steel or steel and gold | Moonshine or Sedna gold, sometimes with steel | Solid 18ct white gold throughout |
| Movement | Quartz | Automatic, Co-Axial | Automatic, Co-Axial, calibre 8521 |
| Bracelet | Steel or two-tone | Gold, sometimes steel-gold | Solid white gold |
| Bizak catalogue range, 28 Sep 2026 | US$2,700 to US$15,810 | US$10,625 to US$36,899 | US$25,999 |
The 28 mm quartz pieces are the entry point into Constellation ownership and the ones most often seen in steel or steel and gold on a bracelet. The 29 mm automatics move into solid Moonshine or Sedna gold with the mechanical Co-Axial movement. The 31 mm white gold, diamond-set case sits at the top of that range: an all-precious-metal automatic with a fully gem-set bezel rather than a gold accent. Anyone choosing between them is really choosing between a everyday quartz watch, a dress automatic, and a piece that reads closer to fine jewellery.
How does the 123.55.31.20.55.003 wear?
At 31 mm and roughly 11.9 mm thick, the case sits close to the wrist and the diamond-set bezel and mother-of-pearl dial catch light rather than dominate the hand. The solid white gold bracelet is heavier than a steel equivalent, which is typical of a gold Constellation and part of what buyers are paying for. The 19 mm lug width and integrated bracelet keep the profile tight; there is no strap option on this reference, so sizing comes from removing or adding bracelet links. It suits a smaller wrist better than the 35 or 39 mm steel Constellations aimed at men, and reads as a dress piece rather than a sport watch.
How much is an Omega Constellation 123.55.31.20.55.003? Market prices in 2026
- Retail. Omega does not fix a single published list price across markets for gem-set, precious-metal Constellation references in the way it does for steel sport models; an authorised dealer can quote the current figure for this exact configuration. Treat any online retail number as a starting point rather than the price at a boutique today.
- Secondary market. On 28 September 2026 a pre-owned example with box and papers was listed on a specialist dealer platform at a US dollar figure in the low US$20,000s. That is one dealer's ask for one watch, not a market average, and it will move.
- Bizak catalogue ask. On 28 September 2026 our sourced catalogue listed the 123.55.31.20.55.003 at US$25,999 brand new, sourced to order.
Those figures describe what we saw and will move. Ask for a dated quote for the exact watch, condition and papers before treating any number as final.
Is the Constellation 123.55.31.20.55.003 a good investment?
Gem-set, precious-metal dress watches from any brand are bought to wear and to enjoy rather than to trade, and the Constellation line has not shown the kind of secondary-market premium that steel sports references from Rolex or Patek Philippe command. Buy it for the case, the dial and the movement rather than for resale upside. Condition and completeness matter more to resale here than to a steel sports watch, because the gold content and stone setting are a larger share of the value; a scratched bezel or a missing diamond changes the maths more than it would on a steel bracelet. If you already own one and want a sense of current demand, ask for a written cash-buy assessment before you decide whether to sell.
Buying a Constellation 123.55.31.20.55.003: what to check
- Box, papers and warranty card. A blank, undated card on a brand-new piece should match the reference and case number; a used piece should carry its original documents where possible.
- Diamond setting. Inspect the bezel stones under good light for security and even spacing; a loose stone is a quality issue to flag before purchase, not after.
- Bracelet links and clasp. White gold is softer than steel. Check every link moves freely and the clasp closes without play, and ask whether any links have already been removed for sizing.
- Movement running. Ask to see the calibre 8521 running with smooth, steady seconds; a watch that has sat unworn for a long period may need a short wind or wear before it settles.
- Dial and mother-of-pearl condition. Natural mother-of-pearl shows some variation across the dial; that is normal. Chips, cracking or an uneven diamond-index setting are not.
- Price against the source. A full-set example offered well under what comparable dealer listings show is the clearest warning sign.
Our authentication process describes what we inspect before dispatch.
Quick answers
How much is an Omega Constellation 123.55.31.20.55.003?
Bizak's sourced catalogue listed it at US$25,999 brand new on 28 September 2026, sourced to order. A pre-owned example on a specialist dealer platform was listed in the low US$20,000s on the same date. Omega does not publish a single fixed retail figure for this gem-set configuration, so ask an authorised dealer for the current price.
What movement is in the Omega Constellation 123.55.31.20.55.003?
Calibre 8521, Omega's automatic Co-Axial movement with 28 jewels and 50 hours of power reserve, visible through the transparent caseback on most Constellation references that use it.
Is the Constellation 123.55.31.20.55.003 solid gold?
Yes. The case, bezel and bracelet are 18ct white gold throughout, with a diamond-set bezel and diamond-set dial indices. There is no steel component on this reference.
What size is the Omega Constellation 123.55.31.20.55.003?
31 mm across the case with a 19 mm lug width, one of several Constellation sizes that also include 25, 28, 29, 35 and 39 mm cases in steel, two-tone or solid gold.
Does the Constellation 123.55.31.20.55.003 have a date function?
Yes, at 3 o'clock, set through the crown alongside the time.
Request an Omega Constellation sourcing quote
Tell us your preferred condition, whether box and papers are required, and your budget and timing, through our sourcing enquiry form. We confirm the specific watch, photographs, papers and final price before you commit. Catalogue entry: Constellation 123.55.31.20.55.003; browse the Omega collection or sell or trade your Omega.
Related reading: Watch nicknames explained · Pre-owned watches collection · Our authentication process · Selling a watch: what to prepare.
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