Omega · Constellation

Strap for Constellation Co-Axial 31 Red Gold / Snow / Diamond Supernova

Takes 20 mm straps. Verified lug width, the straps that fit this model, and answers to the most common questions.

Lug width20 mm
Case diameter31 mm
Reference123.55.31.20.55.008 (aka: 12355312055008)
FamilyConstellation
MovementOmega caliber 8421 hours, minutes, seconds | chronometer, co-Axial escapement
CaseRed Gold

Recommended spring bar

Spring bars Omega 20mm — 1.8mm diameter

Technical match for lug width and diameter · lug 20 mm · Ø 1.8 mm

All Omega spring barsOpen →

Straps for the Constellation 123.55.31.20.55.008 (aka: 12355312055008)

Selected for the 20 mm lug width · workshop selection

All 20 mm straps →

The Constellation 123.55.31.20.55.008 (aka: 12355312055008), seen from the bench

The Constellation represents one of Omega's historic collections in the luxury watch segment. It mounts the automatic calibre 8421 with co-axial escapement and chronometer certification. The reference 123.55.31.20.55.008 indicates a version with hours, minutes and seconds indication.

Frequently asked questions

What is the lug width of the Omega Constellation 123.55.31.20.55.008?

The lug width of the Constellation 123.55.31.20.55.008 is 20mm. This measurement is taken as the linear distance between the outer edges of the lug attachments (lugs) on the case. It is important not to confuse this measurement with the overall case width: the strap must fit perfectly to the attachments, and 20mm is the precise measurement for this model.

Which strap material pairs best with the Constellation 123.55.31.20.55.008 in red gold?

Alligator is the most elegant choice for this model: its natural and uniform grain amplifies the luxury of 18kt red gold. Alligator in cognac or dark brown tones creates perfect chromatic harmony. Shell cordovan is a contemporary alternative that develops over time a deep and fascinating patina, creating an aesthetic narrative parallel to the aging of gold.

How do you change the strap on the Constellation 123.55.31.20.55.008?

The strap is changed through the lateral lug attachments on the case. Use a spring bar tool (specific tool) to compress the attachment pin inside the lug, applying gentle leverage. Once the pin is released from one side, remove the old strap. Insert the new strap by aligning it to the lugs and snap the pin into the opposite hole. If you prefer to avoid doing it yourself, consulting an expert is always recommended.

Can I use an aftermarket strap with my Omega Constellation 123.55.31.20.55.008?

Absolutely yes. Omega, unlike other brands, allows the use of quality aftermarket straps. It is essential that the strap has a certified 20mm lug width. Milano Straps offers a dedicated collection of 20mm compatible straps, crafted to the same excellence standards, with customization options and 18-month warranty.

How long does a leather strap last on a watch like the Constellation?

The durability of a leather strap depends on material, frequency of use, and care. A quality artisanal alligator or shell cordovan strap, worn daily, typically lasts 3-5 years before requiring replacement due to natural wear. Factors such as humidity, sun exposure, and perspiration accelerate aging. Proper maintenance (drying after water contact, avoiding prolonged soaking) significantly extends the strap's useful life.

The next step

The right strap isn't chosen. It is built, together.

From the atelier appointment to delivery, every step is made for those who know that things done well take time. Rare leathers, one piece at a time, eighteen months of warranty.

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Casati Milano · Via XX Settembre 15, Milan · by appointment only