Without question one of the company's greatest contributions to horology is in the area of waterproof cases. The Rolex Oyster case birthed the idea of the modern sport watch as we know it and was a key catalyst for the initial widespread acceptance of the wristwatch.

But before there could be a full-hermetically sealed watch, like the Oyster, there had to be a semi-hermetically sealed one, like this watch.

While many collectors know that Rolex birthed the idea of the Oyster case, far fewer know that Rolex made at least four attempts to create a fully waterproof case before they introduced the Oyster: the Dennison, Semi-Hermetic and "full" Hermetic watches. Very few of these early, pre-Oyster watches designed for water resistance still exist.

Today's offering showcases one their very rare precursors to the Oyster, the "semi-hermetic". It is pleasingly large for the era, measuring 34mm in diameter.

During World War I and in the years that followed, the public's idea of wristwatch changed dramatically. Soldiers, who had discovered how convenient it was to time strategic military operations at a simple turn of the wrist, began modifying their pocket watches, adding with soldered wire lugs a leather strap.

Hans Wilsdorf, one of the two founders of Rolex, was a visionary who early on saw the forthcoming demand for wristwatches. He wanted to produce some of the most reliable wristwatches on the market. But he knew that this required more than well-designed and made movements, and even certifying watches as chronometers - they also needed to be in cases fully protected from the elements.

Wilsdorf recalled telling his staff time and time again, "We must succeed in making a watch case so tight that our movements will be permanently guaranteed against damage caused by dust, perspiration, water, heat, and cold. Only then will the perfect accuracy of the Rolex watch be secured."

Rolex had already tried having cases made by Dennison and by Borgel, two pillars of the case making trade at the time. At the time, Rolex was well-represented in East Asia with retailers in India and Burma and ending up selling many of their hermetic watches to customers in these more tropical climates.

Borgel was a true legend in pioneering waterproof watch cases, and he came up with a new design for a semi-hermetically sealed case. It utilized a three-piece case - body, bezel, and inner movement holder. The threaded bezel screwed down like the lids of a jar.

Within only a couple of years Borgel's hermetic case was supplanted by the full-hermetic, then the new Oyster case, which was patented in 1926. So finding a fine surviving Semi-Hermetic remains a big challenge.

As Rolexes continue to appreciate in value, I think these early pre-Oysters remain under appreciated and undervalued for their rarity and historical significance. I think a time will be coming when their value catches up with the importance and scarcity.

We were fortunate to acquire it with all of its original parts. Its 9K gold case is in pleasing condition. The back has rippling and also band marks in the soft gold from a previously long installed one-piece strap. On the wrist it presents in excellent condition. Its dial was extremely well-restored in vintage times.

Note that the bezel was not fully screwed down when the photos were taken.

Powering the watch is its original fifteen jeweler Aegler Rebberg movement for Rolex.

One of our Master Watchmakers who used to be the watchmaker for an authorized Rolex dealer and was given special training by Rolex at their Beverly Hills Service Center to be an authorized Rolex watchmaker (for many years now Rolex does not "certify" they only "train"), has fully serviced the watch which consists of fully disassembling the movement, carefully inspecting each part, replacing any overly worn components with genuine Rolex parts, installing a new mainspring, reassembling and lubricating the movement, and extensive timing, testing and regulation (a $795 value).

Included with the purchase is a one-year C.O.T. international warranty on the movement and its function and a full-page custom printed Connoisseur of Time Certificate of Authenticity.

Don't miss the chance to add this rare and important Rolex to your distinguished collection.

• Manufacturer: Rolex
• Country of origin: Switzerland
• Year built: c. 1918
• Serial no.: 200,328
• Model: Semi-hermetic / Semi-hermetique
• Functions: Hours, Minutes, Semi-Hermetic
• Designed for: Men
• Case material: Solid 9K gold
• Case markings (inside): Rolex, W & D (For Wilsdorf and Davis, the founders of Rolex) F.B. (see note in case section above for information regarding Francois Borgel), A10M, precious metal hallmarks, 200328
• Case markings (outside): Engraved presentation from 1932
• Case condition: Overall pleasing condition. The back has rippling throughout and also band marks in the soft gold from a previously long installed one-piece strap. One spot of reinforcement only visible from the inside. On the wrist it presents in excellent condition.
• Dimensions: 34mm wide (excluding crown), 37mm long lug tip-to-tip
• Dial: Signed Rolex, silver, black painted Breguet numerals, outer railroad minute track, extremely well-restored in vintage times
• Hands: Original, blued steel "cathedrals"
• Movement type: High grade, Rolex Rebberg 13''', signed Rolex and Swiss made, 15 ruby jewels
• Movement markings: Rolex, Swiss Made, 15 Jewels
• Band: Leather, designed for fixed lug use, fairly lightly worn
• Band width: 14mm
• Crystals: Acrylic, excellent condition
• Servicing: Our Master Watchmaker has fully serviced the watch which consists of fully disassembling the movement, carefully inspecting each part, replacing any overly worn components with genuine Rolex replacements, reassembling and lubricating the movement, and extensive timing testing and regulation (a $745 value).
• Timing: Timed on a state-of-the-art computerized system. Your watch is important to us, and we will take care of it for its lifetime. We provide the best after sale care in the business with an experienced team of four watchmakers all of whom each have over thirty-five years of experience and a large number of parts.
• Warranty: 1-year C.O.T. international warranty.
• Box/Papers: BOX - Connoisseur of Time watch presentation box; PAPERS - Custom printed Connoisseur of Time Certificate of Authenticity
• Returns: 7 days full refund. 100% satisfaction guarantee

We offer a 100% satisfaction guarantee for all of our watches. If you are in any way unsatisfied with the watch we will fully refund the purchase price anytime within 7 days after the watch has been received. Our goal is to exceed our client's expectations throughout the buying experience.

All watches are packaged carefully and mailed double boxed in specially constructed, reinforced shipping boxes designed for high value items. All watches are sent fully insured with signature required. Most of our domestic shipping is done through FedEx. At times we will also use USPS Express Mail, and we can accommodate most requests for your preferred carrier. International shipments are sent USPS International Express Mail or FedEx.

The purchase price will be the declared value of the merchandise on any required customs forms. The payment of all customs duties, tariffs, and taxes are the responsibility of the buyer.

Also note that water resistance of vintage watches can no longer be guaranteed and is not covered under the watch's warranty. We do not recommend getting a vintage watch wet, even one that was originally designed to be waterproof.

To get an idea of how this watch will look on the wrist, please use the Watch Sizing Guide