Reference 231.10.42.21.03.003 is the Master Co-Axial Aqua Terra that ran from 2013 until the 2017 redesign replaced it, and this replica reproduces it at its original 41.5mm. The teak lines on this generation run vertically, top to bottom, which is the quickest way to tell it apart from the horizontal-teak dials Omega builds today. The date sits at 3 o’clock in the classical position rather than at 6, and the dial reads MASTER CO-AXIAL CHRONOMETER, not Master Chronometer.

Key Specifications

• Reference: 231.10.42.21.03.003
• Case diameter: 41.5mm
• Dial: sunburst blue with vertical teak pattern
• Case material: stainless steel
• Crystal: sapphire with anti-reflective treatment
• Bracelet: stainless steel with fold-over clasp
• Movement: automatic Master Co-Axial, date at 3 o’clock
• Water resistance: 150 meters

The date sits in the traditional 3 o’clock window here, cut straight through the vertical teak lines. Omega only moved the aperture to 6 with the 2017 cases, so a date at 3 on an Aqua Terra is a reliable marker that you are looking at a Master Co-Axial reference rather than a Master Chronometer one.

Design & Finishing

Blue-dial watches have dominated the market for the past several years, and the Aqua Terra version delivers a shade that shifts between deep navy in low light and a brighter royal blue in direct sun. The applied hour markers feature a rhodium-plated finish that contrasts sharply against the blue surface. The 41.5mm case maintains a slim profile that slides under a shirt cuff, which is where this reference outperforms larger dive-oriented models in daily versatility. Compare the proportions against the 42mm 231.10.42 for a slightly larger alternative. The full range sits within the Seamaster lineup, covering sizes from 38mm to 43mm across the Aqua Terra and Diver sub-families.

On the Wrist

The 41.5mm diameter paired with moderate lug-to-lug length makes this among the most wearable Seamaster configurations available. It does not demand attention the way a 44mm Planet Ocean does, but it carries enough presence to register as a serious watch on the wrist. The steel bracelet tapers from the case to the clasp, which improves comfort and gives the profile a more refined shape than non-tapered alternatives. This replica Aqua Terra 231.10.42.21.03.003 balances sport capability and everyday elegance within a single reference.