Omega Seamaster wristwatch, 1956

Last Updated on June 8, 2024 by Jason

This vintage Omega Seamaster wristwatch has a calibre 501 20-jewel automatic movement that works well and keeps time accurately. The movement is fully signed by Omega and the serial number 15,832,615 dates back to 1956. The Seamaster is one of those iconic brands that every true watch connoisseur wants to have in their collection. I am no different, the Seamaster is a “must-have” vintage watch. In this post, we take a look at a relatively early Omega Seamaster in stainless steel, with one of the most reliable automatic movements from the 1950s & 60s, the Omega calibre 501.

Vintage Omega Seamaster wristwatch, 1956.
Vintage Omega Seamaster wristwatch, 1956.

The Omega Seamaster brand

The Omega Seamaster is an iconic watch brand, much admired by vintage watch collectors and modern enthusiasts. The initial water-resistant design combined elegance with durability. As a result, it was suitable for both formal and everyday use.

The Omega Seamaster was introduced in 1948 to celebrate Omega’s 100th anniversary. It was inspired by Omega’s involvement in creating the robust Dirty Dozen watches for the British military during World War II. The first Seamaster models featured an innovative O-ring gasket, which provided superior water resistance compared to traditional lead or shellac gaskets.

In 1957, Omega launched the Seamaster 300, which was specifically designed for divers and professionals working underwater. It featured a robust case, a rotating bezel, and improved water resistance. Later, in 1969, Omega introduced the helium escape valve in the Seamaster 600 model, addressing the issue of helium buildup in professional diving watches.

Omega revitalised the Seamaster line in 1993, with the Seamaster Professional Diver 300M. It included a distinct wave-patterned dial, skeleton hands, and a helium escape valve. It became widely popular and is notable for featuring in the James Bond film series.

Hippocampus logo

The iconic seahorse logo, also known as the hippocampus, was first used on the case back of Omega Seamaster watches in 1958. This emblem, designed by engraver Jean-Pierre Borle, was inspired by the traditional imagery of seahorses seen on Venice’s gondolas. It symbolises the Seamaster’s connection to water and its suitability for aquatic activities. Unfortunately, this particular watch pre-dates the release of the logo by two years and has a plain case back.

Omega calibre 501

The watch is powered by the Omega calibre 501 movement. This top tier calibre is one of the first of the respected 500’s series movements. It has 20 jewels and is considered one of the finest mass-produced automatic movements from the era. The copper coloured movement has 20 jewels, a straight line lever escapement, monometallic balance, an Incabloc shock protection system, a self-compensating flat balance spring and a micrometer regulator. The movement is 12.5 ‴ lignes (28 mm) in diameter and has a power reserve of 46 hours. Omega produced the calibre 501 from 1955 until 1960. The Caliber 501 is highly regarded for its accuracy and reliability. Notably, the calibre 501 was the first full rotor-driven movement by Omega, contributing to its noteworthy reputation.

Omega calibre 501.
Omega calibre 501.


The watch case measures 34mm in diameter excluding the winding crown and the lugs. The case is “Denisteel” stainless steel and it is in good condition with just some light marking and a little gentle unevenness to the back. This is nothing more than patina and adds to the character of the watch. The inside of the case back has the Omega logo. As a nod to authenticity and originality, the watch has the original signed Omega Seamaster winding crown. The unsigned acrylic crystal lens is in good condition. The silver two tone dial has light freckling. The watch comes with the original dauphine shaped hands and centre seconds hand.

Denisteel blank case back.
Plain Denisteel case back.

Denisteel case

Denisteel was a trade name registered by the Dennison Watch Case Company in 1934 to describe its stainless steel watch cases. Stainless steel was developed by Harry Brearley of Thomas Firth & Sons in 1912. Initially, stainless steel was used for cutlery. However, by the 1930s, due to the Great Depression, watchmakers began to look for cheaper alternatives for watch cases than gold, silver and even nickel. As a result, watch cases began to be made from stainless steel in the early 1930s. Today, we most commonly find the Denisteel stamp inside case backs from the 1940s to the 1960s on UK market models by Omega, Rolex and IWC.

Beads of rice bracelet

The watch comes on a “beads of rice bracelet”. The raised Omega logo is stamped on the outside of the clasp. It is also signed on the inside of the clasp. There are some general light surface markings to the clasp and bracelet, but this is expected on a vintage timepiece. The watch currently fits an 18cm wrist although there are extra links to extend it to a larger wrist. The Omega n12 “beads of rice” bracelet is adjustable to fit different wrist sizes through link removal/addition and clasp micro-adjustments.

Omega "beads of rice bracelet".
Omega “beads of rice bracelet”.

The “beads of rice” bracelet is named for its distinctive design. It features small, rounded stainless steel links that resemble grains of rice. The “beads of rice” design is known for its elegant and vintage appearance. It is typically associated with vintage watches from the mid-20th century.


I must admit this watch is tempting. A vintage Omega Seamaster is high on the list for my collection. Vintage Omega’s are so well made and robust that they still make excellent daily wearers. However, in my mind, the classic Seamaster has the hippocampus logo on the case back. This watch is totally legitimate and its plain case back is accurate for the date of the watch. However, I want that iconic hippocampus logo. That isn’t to say I would turn this vintage watch down as a gift and I could see myself wearing it. However, if I am buying my one and only vintage Omega Seamaster, it needs that hippocampus on the case back.

Leave a Reply

Your email address will not be published. Required fields are marked *