A Look into the Aquastar Benthos 500

A couple of years ago I experienced a growing interest in vintage divers, especially from the sixties and seventies. These decades saw the development of the professional diver's tool watch. Most people are familiar with the Rolex Submariner, a classic developed in the fifties and still in production today. But Rolex wasn't the only producer of quality dive watches. Another, lesser known producer was Aquastar and their Benthos 500 professional diver's watch.

The Aquastar Benthos 500. Pressure tested to depths of 500 meters, a record for a diver watch at the time. This is the variant with blue bezel and dial. Pic: WatchUSeek.

The Company

Aquastar was founded in 1962 by Frédéric Robert, an experienced Scuba diver. As the name suggests, they specialized in diver's watches. Soon they expanded their production to also include regatta watches, but all the time their main focus was the development of quality watches for the emerging Scuba diving community.

Aquastar advertisement from the late sixties, early seventies. Shows the Benthos, Seatime and Regate model ranges, the latter a watch with a regatta countdown mechanism. Pic: WatchUSeek.

Frédéric Robert did not stay for long though. In 1970 he moved to Omega and became an advisor in the development of the Seamaster models. The company survived the eighties and nineties and still produces watches today, mainly regatta watches.

The Dial

The Benthos 500 could be looked upon as Aquastar's flagship in the sixties and seventies. It was the first watch pressure tested for depths up to 500 meters, hence the "500" in the name of the model. It came in two configurations, one with black dial and black bezel and another one with blue dial and bezel. I have seen watches with a combination of blue and black, but I'm uncertain if this is original from the factory or a "put-together" done at a later time.

The Aquastar Benthos 500, two blue ones and two black ones, the known configurations of this model. Pic: WatchUSeek.

The production period for the Benthos was from 1962 to 1972, although it is hard to pinpoint the production year exactly with these watches. They used modified A. Schild 1902 and 2162 movements, and as far as I know these movements did not have serial numbers that could give us the production year.

The dial and outer rotating bezel. The watch is actually a chronograph with a orange minute counter at the center of the dial and not in a sub dial as found in most other chronograph models. Pic: WatchUSeek..

The dial is a classic diver dial, legible and heavy on the lume for enhanced readability in murky waters. It is a balanced dial with enhanced minute markers every five minutes. The broad stick hour and minute hands adds to the legibility of the watch, as does the second hand. The one thing that stands out is the fourth hand shaped like an orange arrow. This is the minute counter started with the pusher at four o'clock. The diver used the combination of the bezel ring and this minute counter to time the dives.

The case of the Benthos is a classic C-shaped divers case with a raised bezel ring. It usually came on an isofrane strap or a steel bracelet. Pic: WatchUSeek.

During the production period the Benthos was also co-branded with Tissot. These watches had the Tissot logo together with the Aquastar logo on the dial.

The co-branded Aquastar/Tissot Benthos 500. It is thought that this variation was mostly distributed in Australia. Pic: www.thewatchspotblog.com.

Seems like most of these co-branded watches was sold in Australia, since most co-branded ones are found here. If anyone has more information on this co-branding and the history behind it please let me know!

Some people say that Lemania also produced these watches with the Lemania logo on the dial. I haven't been able to confirm that, so my conclusion for the time being is that there are no such Lemanias.

I have found Benthos 1000 (later generation) with Lemania on them but not 500s. It is believed though that Lemania put the Benthos 500 watches together on behalf of Aquastar as a third party service. I find it somewhat odd that Lemania would put together watches without Lemania movements in them.

The Case and Crystal

The case is a heavy C-shaped case with the Aquastar-logo on the back. This type of case is typical for the late sixties, early seventies.

The case back with the Aquastar logo. I have a weak spot for vintage cases where the logo is integrated into the case back. Pic: WatchUSeek.

The divers in this period often had this type of case or the Brevet compressor case. Luckily for me I like both cases, although in the beginning I had problems with these C-shaped cases. But here the case is somewhat balanced out by the raised bezel ring. This makes the watch look "rounder" compared to a watch were the bezel is integrated in the case. The latter exemplified by the Aquastar Seatime in the advertisement above.

The caseback came in two different variations, one with the Aquastar logo resting on a polished surface, the other where the logo is resting on a pepple blasted surface. On the caseback you will find the reference number, 1002 just below the logo.

The two different case backs. The pebble blasted surface underneath the logo to the left, the polished one to the right. Pics: WatchUSeek.

The crystal is a 4mm thick specially designed crystal that is rare and hard to come by. Should you need a new one it is relatively expensive to have one made.

The Bezel

It it not confirmed by Aquastar themselves, but it seems like the Benthos 500 came with two different bezels apart from the blue and black color configuration. One bezel is with a silver colored inner ring and the other is without this ring.

The Bezel configurations of the Benthos 500. To the left the somewhat smaller bezel without the silver colored inner ring. To the right the one with this ring. The case appears bigger with the bezel to the left. Pics: Aquastar and WUS.

Unfortunately the bezel insert is hard to find, should you need a new one. They are pretty rare and hard to come by, but I've read somewhere that it is possible to fit a Seiko one to the watch. Not original, but a solution all the same, should the bezel be in a bad shape.

The Movement

Inside the Benthos is the AS 2162 or 1902/8 movement, modified to support a center minute counter (the orange hand). AS stands for Adolph Schild, the producer of the movement. Schild produced and supplied many watch manufacturers with movements throughout the 20th century. Adolph Schild was the brother of Urs Schild, the founder of the movement production company later named Eterna (ETA).

The AS 2162 automatic movement. This was a standard movement widely used by Swiss watch manufacturers in the sixties. The one in the Benthos was modified to accommodate a center minute counter. Pic: Thewatchspot.co.uk.

The company died together with so many others during the quartz revolution, and had to close in 1983. The way I see it, the part situation is ok. I have a Glycine Airman Special with an AS 1701 inside, and both times I've had it to service, parts did not represent a problem, despite the closing of the factory way back in 1983. I guess it is on account of the wide distribution of these movements especially in the sixties. There are probably plenty of parts around still.

Caveat Emptor

If you are considering investing in an Aquastar Benthos 500, there are a few things to consider. Given that the watch in question checks out with regard to originality, some of the parts are hard to get by in the second hand market:

• If the crystal is scratched and damaged, the wait for a used (or New Old Stock) one could be long. There is a possibility to have the crystal made, but the cost is relatively high.
• If the bezel insert is damaged there could be a problem getting a nice used one. An option is to use a Seiko bezel insert, but then you technically would have a frankenwatch.

Many of these watches were used by divers and as such the conditions vary. The ones in original near-mint condition do not show up often, and when they do they are relatively expensive. One option is to go for a restored one. 

Professional restorers can effectively set the watch back to "like new" condition. But it is important to use someone who understand what an "original" restoration means. International Watch Works have experience restoring Aquastar Benthos 500s, and would know how to proceed to get the best possible result. Aquastar themselves do not restore or service old pre-quartz models as far as I know.

There is a weakness with regard to the modified minute counter. A service usually fixes this. As such, it is important to buy a watch that has been serviced, alternatively take service costs into account when agreeing on a price.

So, to sum it up, it is important to check the crystal and bezel with regard to condition. Also check if the watch has been serviced and returned with a working minute counter. The crystal should be without major cracks that cannot be buffed out. The bezel should be in an agreeable condition as well, possibly check for originality of the insert. It could be a Seiko.

A Trip to Geneva and Beyond

This summer I had the opportunity to travel to Geneva and Switzerland. Unnecessary to say the main focus was horology and wrist watches. I only stayed there for five days but got to see a good deal of the country and visit some of the main horological shops and museums. 

I flew to Geneva and used the city as a "base" to travel to other parts of the country. After a few days in Geneva I did a road trip to Basel with two stops in between; Bienne and La Chaux-de-Fonds. This road trip takes you through "watch valley" or Vallee de Joux, an area filled with beautiful vistas and horological history.

Shopping

First of all, Geneva is not that exciting as a city in itself. There are parts worth visiting (the old town is nice) but to be quite honest: the city does not have all that to offer except very expensive shopping and horological museums.

The two main shopping streets are Rue de Marche and Rue de Rhone. The ADs for all the major brands are situated along Rue de Rhone. A good place to start trawling the ADs is Place du Port (a square along the Rue de Rhone) and the Bucherer store situated there.

Bucherer, Rue de Rhone, Geneva. AD for Rolex, Tudor and a bunch of other brands. Only brand new watches, no vintage or second-hand. This goes for all the AD shops along the Rue de Rhone.

Had a look at the new Tudors here, and the service was good and informative. Although the clerk got a little defensive when I asked about Omega. He said that he knew absolutely nothing about Omega, and made it very clear that they did not sell the brand at Bucherer. Nothing? Strange thing to say, being from Switzerland and all.

Anyway, just a few blocks down the street I found the main Omega store. Again, the service was very good. A young Asian gentleman helped me out, and the lack of knowledge was compensated with an abundance of enthusiasm. A very nice visit.

A really nice Speedmaster 57 housing the co-axial 9300 caliber courtesy Omega Store, Rue de Rhone. In a reasonable 42mm diameter case as well. Even for a vintage collector this piece is very tempting! 

Needless to say, I did not visit all the stores along the Rue de Rhone. There are many and all the major brands are represented. I visited the ones I found most interesting, Breguet being one of them. I noticed that Breguet also had a clerk of Asian decent. Probably to better serve the influx of Asian tourists, especially from China. The last two visited was the official Jaeger LeCoultre and Panerai stores. And I must say, the service was excellent in all of them.

Rue de Marche also has its share of watch stores, but mostly with mid-price brands like Tissot, Frederick Constant, Rado and so forth. What about vintage? Well, there are a few stores but not many, and I had to ask around a bit before someone gave me the directions to one of them: Au Vieil Horologer.

One of three vintage watch stores in Geneva: Au Vieil Horloger is found in Rue du Cendrier, on the other side of the river from Rue de Rhone

Quite a few pieces on display and all of them in the window. The proprietor Olivier Guttly was forthcoming and finally someone I could talk "vintage" with. I asked him about the lack of second-hand and vintage stores in Geneva. He said there were quite a few some years ago, but after the major auction houses had established themselves here, they had disappeared one after the other. Most collectors and sellers prefer to sell their pieces through these houses, in auctions usually held three or four times a year.

At Au Vieil Horologer I had a look at several Omega Seamasters, mostly from the fifties, quite reasonably priced considering their recent service and the warranty offered if purchased. Some high-end vintage also, like this Audemars Piguet Royal Oak, A-series, ca. 1973.

AP RO, A-series, ca. 1973 courtesy Au Vieil Horologer. A Genta classic, and quite daring when it came in the beginning of the seventies.

While at Bucherer I asked about vintage stores, and they mentioned a place called Ponti. Mr. Guttly also mentioned Ponti, and was kind enough to give me directions. Fortunately downtown Geneva is pretty compact and everything is within reasonable walking distance. Soon I found myself inside Mr. Laurent Ponti's second-hand and vintage store.

As always, the service was flawless. He had both second-hand and vintage on offer. At the time, he had quite a few Rolexes, including the famed Submariner 5513, pictured below.

Rolex Submariner 5513, mid-sixties in excellent condition, with nice patina and bezel nicely faded to a blue-grey color. Courtesy Ponti joaillier, Geneve.

He also had a few vintage Rolex GMT Masters and one Breitling Chrono-Matic for sale. Apart from that it was mostly second-hand and quite a few Rolexes. So, if you are into Rolexes, this is the place to go.

After a nice chat about watches and our shared love for vintage ones, Mr. Ponti was so kind to give me directions to another vintage store in Geneva, the Horlogerie Ancienne. This one is situated on Boulevard du Theatre, not far from the Patek Philippe Museum.

Horlogerie Ancienne, nice vintage pieces beautifully presented among tools and workbenches still in use by the proprietor, who has been in the trade for more than 40 years

Soon I found myself chatting away with the Fabien, the son of the proprietor. A good selection of vintage pieces in excellent condition, among these a couple of Omega Speedmasters and Flightmasters, a Rolex Daytona from the early seventies and a couple of really nice Jaeger LeCoultre models from the late sixties/early seventies.

Jaeger LeCoultre Memovox Automatic from the late sixities, courtesy Horlogerie Ancienne, Geneva. This was NOS (New Old Stock) and absolutely flawless.

Mr. Desbiolles told me that his brother also was in the trade, operating out of Miami. A real horological family. The service was excellent and we had a nice chat about vintage watches, the thrill of collecting and the madness nowadays when it came to vintage Rolexes. I must say that the shop was an experience in itself with its workbenches and miscellaneous horological paraphernalia. 

Inside Horlogerie Ancienne and one of the workbenches there. With all the different horological tools and instruments, the store was truly a magnificent experience

They even had a really nice JLC "Snowdrop" on the original bracelet. I have only seen these ones on the Internet, and it looked way better in real life. A rare piece in very nice condition.

Jaeger LeCoultre "Snowdrop", early seventies. Courtesy of Horologerie Ancienne. A rare gem in excellent condition and with the original bracelet. This is a Memovox and has the "cricket" alarm also.

Although a short stay, I managed to locate these vintage stores. All the proprietors were forthcoming and knowledgeable, but most importantly: watch enthusiasts. I really enjoyed meeting them.

I would be nice to be present at one of the auctions as well, but have to save that one for another time. Please feel free to comment if you have other vintage stores that should be visited in Geneva. I am quite sure I will come back not long from now.

Museums

There are several horological museums in Geneva, the Patek Philippe Museum being the most famous and rumored to be the best. Very much a brand museum it still has some early pocket watch pieces from other makers on display. All in all there are a lot of pocket watches here, far more than wrist watches. Don't get me wrong, these pocket watches are very fascinating and not to mention impressive.

The Patek Philippe Museum. You will find it in rue des vieux-grenadiers. A must when you visit Geneva.

I went to Bienne on a Sunday so any shopping was out of the question. But the Omega Museum was open. As a vintage Omega collector, the museum is a must, but I would say that even though you are not a Omega devotee there are plenty of stuff there to enjoy and marvel at.

The museum is located at rue Jacob-Stampfli 96, right across the road from the main factory building. I visited the museum in August which is off-season in Switzerland. As such, I had the museum to myself. But even better, I had the staff's full attention. 

The Omega Museum in Bienne (Biel), rue Jakob Stampfli 96, is a very unassuming building. You will notice the large original factory building across the street first. When you see that, you know you are close.

On this particular day in August Mr. Loic Voumard was in charge. Very helpful and service-minded! And since he was wearing an absolutely beautiful Omega Speedmaster 105.012-65 in original condition we had something to talk about even before I entered the museum.

Omega Diver Prototypes (click to enlarge). Omega has been producing divers since 1932.  Personally I have a weak spot for pilot and dive watches, and as such this display was fantastic. Here we have further developments of the classic "ploprof" and "SHOM" watches.

I must say I am impressed by the overall quality of the Omega pieces throughout the company's history. For me, there are no other brands who can show such a high quality and desirability in their designs. But then again, I am a fanboy.

On the way back from Basel we had a stop in La Chaux-de-Fonds and The International Museum of Horology (Musée International d’Horlogerie). La Chaux-de-Fonds is situated in the canton of Neuchatel, considered the birthplace of Swiss horology. Some of you might now that COSC also are situated here.

Musee International d'Horlogerie in La Chaux-de-Fonds, in many aspects the birthplace of the Swiss watchmaking industry back in the mid 19th century

A fantastic museum were you can spend hours on end looking at complications, beautiful, historical and important pieces with plenty of really cool displays explaining the workings of an automatic movement or the principle of the mainspring and escapement.

Links and Addresses

Bijouterie Bucherer

Rue du Rhône 45, 1204 Genève

OMEGA Boutique
Rue du Rhône 31, 1204 Genève

Au Vieil Horologer

Rue du Cendrier 28, 1201 Genève

Ponti joaillier

Rue du Port 3, 1204 Genève

Horlogerie Ancienne

Boulevard du Theatre 7, 1204 Genève

Patek Philippe Museum

Rue des Vieux-Grenadiers 7, 1205 Genève

Omega Museum

Rue Jakob-Stampfli 96, 2500 Bienne

Musée International d’Horlogerie

Rue des Musée 29, 2300 La Chaux-de-Fonds

Buying a Vintage Omega Seamaster 300

In this article I will share my experiences searching for and buying a vintage Omega Seamaster 300 (SM300). Most of this is a result of thrawling the Internet and this can be looked upon as a collection of these findings. Among collectors buying a SM300 is regarded as a relatively risky endeavor. There are many frankenwatches out there, or even worse: outright fakes. 

Frankenwatches are watches where all parts are produced by Omega, but from different models and different time periods. As always, it is all about knowing the model, decide what condition you'll find acceptable, and finally; what you would like to pay for a piece that meets your standards.

There's a lot of useful information about the SM300 on the Internet. You will find dedicated sites and threads in various watch related discussion forums going into details about the various models of vintage SM300s. Some of this information is easy to google, some is not. And some information get pulled from the net after some time. This article is an attempt to gather some of this information in one place and maybe preserve it for some time.

Some Preliminary Remarks

This is guide buying a vintage Omega Seamaster 300 and much of it is about finding a piece with parts that can be ascribed to the same time period. Note that I'm not saying the same year.

This is because it is assumed that Omega in the sixties produced parts for these watches independent of planned assembly and shipment. Cases dated 1966 can be found housing movements from 1964 (if in 1966 the movements produced in 1964 where still in stock). 

Omega did not follow a tight regime with regard to parts and production year. Of course you will find exact matches, but it should not be a deal breaker if it isn't so. So how to decide if it is a franken? Well, if parts on a particular piece transgresses reference boundaries, typically parts that are specific for one reference found in another reference, you are probably looking at a frankenwatch. Reference in this case is the model number.

An example could be a date window on a 165.024 which again tells you that the dial or case is wrong. Or, if the case is from 1963 and the movement is from 1969 or 1970. Personally I set a maximum of 2-4 years difference when it comes to the production year of the different parts of the watch. So, in these cases you could assume it is a franken.

Model Variations and Scope

What models are we considering? The SM300 has been produced since 1958 and is still a part of the Omega collection. This guide looks at the so-called second generation of SM300's, reference 165.024 (no date) or the 166.024 (with date).

For many collectors considered THE Omega Seamaster 300, ref. 165.024 (no date). A classic and a rival to Rolex Submariner 5513.

Same model, this one with date (ref. 166.024) and an aftermarket mesh bracelet. Big triangle at 12 o'clock, introduced ca. 1967.

These second generation references were produced from ca. 1962 up until 1969. It came in both civilian and military versions, the latter given to service-men in the British Royal Navy. The military one had the ubiquitous "T" on the dial and a military serial number engraved on the outside of the caseback. These watches are very rare and subsequently very expensive. Since they are both expensive and desireable, there are many fakes out there. They are probably even harder to judge when it comes to originality, and as such I have chosen not to include them in this guide. For those of you thinking of investing in such a piece, there are many resource sites on the net dedicated to these military variants.

A fully restored SM300 from WatchCo, Australia. These restored ones are not covered in this article. They are usually easy to purchase as long as proper paperwork accompanies the watch.

Back in the sixties many of the SM300s were used for its intended purposes; diving. 40-50 years later, many of these watches bear marks consistent with this, typically dented cases, cracked bezels and water-damaged dials, hands and movements. But in many instances the watch is salvagable, and many of the pieces available in the market place today are restored ones, usually done by independent watchmakers (like Australian WatchCo) or Omega in Bienne, Switzerland. This article does not cover such restored pieces. Aquiring such a watch is fairly easy and do not require much due dilligence besides getting the proper paper work for the restoration work that has been done.

As of 2012 Omega has condoned independent watchmakers restoring vintage SM300s. But it seems there is a policy change in the making and Omega (along with other major manufacturers) is limiting the possibilities for such watchmakers to restore these watches. There is this story of a buyer of a restored WatchCo SM300 who got his watch confiscated by his country's custom authorities as a franken/fake by order of Omega. Fortunately he got a refund from WatchCo. It will be interesting to see how both restoration and service of vintage Omegas will be performed in the future. If Omega, Switzerland is the only option, it is reasonable to assume there will be a price hike.

To sum up: We will be considering the references 165/6.024, production period 1962-1969. The different parts of the watch will be discussed in detail and checked against model and reference numbers.

Using the Reference Number to Identify the Model

But first things first: identifying the model with the help of the reference number. If this is not a part of the sales description it should be asked for and accompanied with relevant pictures. The reference number can be found on the inside of the caseback. These reference number is indicated somewhat differently, below are the known variants.

Example 1: Six digits, no period after third digit

Example 2: Six digits, period after third digit

Example 3: Six digits and production year

The reference number should be six digits (please note: a modern replacement caseback would have 7 digits, usually and additional zero after the period, e.g. 165.0024).Some casebacks also have the letters SC stamped into it. SC stands for "seconde centre", and means the movement has a centralized second hand.

All casebacks above are legit and constitutes an original caseback from the period in question. Please note that a modern replacement mentioned above is genuine Omega, but not consistent with the time period. Technically a watch with such a caseback is a franken. I will leave it up to the buyer to decide if this is ok or not. Some collectors would turn such a piece down.

Movement and Production Year

The serial number on the movement gives us the production year. The caliber number should also be found on the movement.

Serial number 23797539 indicates production year 1964/1965. This is caliber 552 (w/o date). The reference number and the production year is subsequently used to establish if the rest of the watch is consistent with the time period.

The movement should be a caliber 552 for the 165.024 and a 565 for the 166.024. The last one with date and introduced ca. 1967.  Please note that there are examples with caliber 550. These are SM300s sold in the American market and Omega chose this caliber for duty and taxation reasons. It was cheaper to import caliber 550 instead of the usual caliber 552. The same goes for the date version it seems, although this is not confirmed by Omega. For taxation reasons there are SM300s sold in the US with caliber 563.

Any other movements, and the watch is a franken. Also, be aware that there are examples of watches were the dial is w/o date and the caliber is 565 and vice versa. These watches are frankenwatches.

We have the following SM300 serial numbers for the time period:

• 1963 - 20'000'000 
• 1964 - 21'000'000 
• 1965 - 22'000'000 
• 1966 - 23'000'000, 24'000'000
• 1967 - 25'000'000 
• 1968 - 26'000'000, 27'000'000 
• 1969 - 28'000'000, 29'000'000, 30'000'000, 31'000'000 
• 1970 - 32'000'000 

Please note that there are fluctuations with regard to serial numbers, reference numbers and production dates. There are legit non-frankens with a movement produced in 1967 in a case marked 165.024-65. The general consensus is that this is due to the batch production of the different parts of the watch where the assembly was done at a later stage with the parts available at that particular moment. But the fluctuations should not span more than 2-3 years. If so, I would suspect a franken although there is a chance the piece is legit.

The Dial

Next: The dial. It is important to make sure that the dial is original and to establish the level of restoration (if any) of the dial. Given that we are looking at an original Omega dial, the latter will affect the valuation of the piece. There are several aspects with regard to the dial that need to be checked out. One thing is the hour markers, minute markers and the 6, and 9 digits. One tell-tale of a fake dial is stubbies. Stubbies are minute markers underneath the hour markers, see illustration below.

FAKE! An example of so-called "stubbies", i.e. thin minute markers underneath the fat hour markers. Notice the lumina color difference on the dial compared to the second hand. I'll get back to that.

It is also important to check the font of the 6 and 9 numbers. They serifs should be open and not closed, closed signifying a fake dial.

FAKE! Closed serifs at 6. Original dial to the right. Also notice the small hole in the lumina on the original one. This is a sign that the watch has not been re-lumed and has its original lumina

FAKE! Closed serifs at 9. Original dial to the right. Notice the stubbies on the fake one as well.  Sometime the fakers manage to double their mistakes.

It is also important to check the date window on the date versions (166.024). The window should have a white frame surrounding it. If it doesn't have a frame it is either a fake or a regular non-diver Seamaster dial that has been repainted as a SM300 dial. the date window cut-out should also be angled, see illustration below.

FAKE! No white frame surrounding the date window. Original to the right. Also notice the way the date window has been cut out on the original one. The cut should be angled inwards. 

Also check the font of "Seamaster 300" and compare it to a known original. When doing this it is quite easy to spot a bad redial. The luminated markers should also be checked. A dial could be re-lumed (some collectors would turn such a piece down) and this should be reflected in the price. If it has a pin-point hole at the bottom of the marker at 12 and 6, it is probably not a re-dial. When re-dialed this hole get covered up.

In 1967 Omega introduced the "Big Triangle" dial. This was a dial where the 12 was removed and replaced with a big triangular marker.

Seamaster 300 "Big Triangle" released ca. 1967. The Big Triangle was originally intended for military versions of the SM300 but came on civilian versions as well.

If the case and/or the movement is from the early sixties I would be a litte bit suspicious. But I think versions with the big triangle dating from 1965 and 1966 are ok, given the way the watches at the Omega factory were assembled.

Last but not least, check obvious things like misspellings (!), variations in font sizes and the placement of the Omega logo, 300 and "T Swiss Made T". "T" stands for tritium and this replaced radium lumination in the late 50s early 60s for obvious reasons. As I understand it, you will find dials from the early production period with tritium lumination, but without the "T". But then again, it could be a replacement dial from a first generation SM300 and as such a frankenwatch.

Hands

There are two legit hand variations; sword and baton (or "candlestick"). The baton hands were used on early models, usually dating from 1962-1964. The second hand is the same used on the pre-moon Omega Speedmasters, luminated triangle at the top and a droplet below the base of the hand.

SM300 with baton (or "candlestick") minute and hour hand. Notice the re-.lume of hands and dial. Nicely done, but not to everyone's liking.

SM300 with sword hands. Or hand, as it is the hour hand that is shaped like a sword. The minute hand has the baton shape.

There is a belief that Omega had a transition from baton to sword hands around 1965. But as discussed previously, Omega used parts as long as they were in stock. It is highly likely that Omega used baton hands after 1965, but I would be suspicious of pieces with baton hands dating from 1968 and 1969. The same goes for watches from 1963 and 1964 with sword hands. One way to alleviate that suspicion is to check the patina on the hands and the dial. Differences in color might be an indication of hands (or dial) replaced sometime between the assembly date and now.

As a curiousity there are SM300s with dauphine hands as well. These were considered frankens, but fortunately this configuration showed up in an Italian catalog from 1964, and as such proved the fact that there were a transition from the early first generation sM300s with regards to minute and hour hands.

Correct, but very rare early second generation SM300 with dauphine hands. These hands are usually found on first generation SM300s (CK-2913)

The dauphine hands were typical for reference CK-2913 and this proves that the hands were used on 165/6.024 references as well.

Bezel

The bezels came in five different versions during the production period. The changes are mostly font variations and the thickness of the font and minute markers. There are discussions on various watch forums whether certain bezels would be misplaced on some models, i.e. a franken. The conclusion at the time being seems to be that all the bezel variations are legit and used throughout the period. 

SM300 bezels 1963-1969. It is assumed that all of them were released 1963/1964 and as such legit bezels for the whole production period. But bezel D was released in 1969 and should be regarded with suspicion on the earliest models.

But there are certain bezel versions that seem to be more used on earlier models than others, especially the thin fonts on variants A and B in the picture above. But since this is not conclusive, I would recommend not to make this a deal-breaker.

The lume on the bezel should be on the numbers and the hour markers. The minute markers should not be lumed. Also, the patina of the lume should be consistent with the patina on the dial and hands. Fake bezels often doesn't have lumed numbers and hour markers. Instead of lume they are painted in a yellowish tint, see example below.

FAKE! Bezel with yellow, non-luminated number and hour markers. This also has a fake dial with stubbies and closed serifs at 6 and 9. A proper fake!

The bezel should be bi-directional and with one click pr. minute, i.e. 60 clicks. Fake bezels sometimes have more clicks than this, typically 120 clicks. One thing is to count, another way is to actually see the reverse side of the bezel ring illustrated below.

FAKE! The bezel should have 60 bi-directional clicks. Fake bezel below (120 clicks), original on top.

Crown

The crown came in two variants; Naiad crown and the screw down crown. The first one had a self-sealing system and got tighter the farther below you went, the other one is a classic diver crown tightened once and for all by screwing it into the case.

The Naiad was fitted to SM300s up until 1967. The screw-down after was fitted after that. As always, earlier versions with screw-down should raise suspicion. The same goes with later models with a Naiad crown. Although this, according to my experience is rarely seen.

Correct examples of the SM300 crown. Naiad below and to the right. Notice how the Naiad crown fluctuates more with the case than the screw-down crown.

Case and Caseback

The outside of the caseback should have an engraved sea monster with an Omega logo underneath.
Circling the logo: "Certified High Pressure Waterproof" and "Seamaster" also engraved.

Original caseback, where the following should be checked: "Certified" not "Certifed", A with a flat top, same height "Sea" and "Master"

The following should be checked:

• Fake casebacks sometimes have "Certified" spelled wrong (yes, really)
• The A in "Waterproof" should have a flat top, not a pointy one
• Some fakes have problems with "Seamaster": The height of the lettering should be the same, with the M a fraction higher

FAKE! A caseback with all the hallmarks of a fake. It is enough with one of these, but sometimes the fakers manage to make a collection of them on one caseback

It is also important to evaluate font-type and the depth and looks of the engravings to sure. If it looks like the engraving was made yesterday, it is probably true.

The early casebacks had rounded edges, later ones had an angled edeges, as illustrated below.

Correct caseback profiles.  Early caseback on top (rounded) and later version below. Both are correct but be suspicious of early ones with angled edges and vice versa

Bracelets and Leather Straps

Back in the sixties when buying a SM300 the customer had the choice of leather strap og steel bracelet. There is reason to believe that sometimes this was an option offered at an authorized dealer (AD) and the choice was fitted the watch accordingly. Leather straps were easily worn out and as of yet I haven't seen a NOS SM300 with the original leather strap and buckle attached to it. Steel bracelets on the other hand can be found on SM300s, but usually these are later original Omega ones or generic after market ones. The original bracelets that came with the SM300 are as follows:

• Bracelet 1506 (end piece no. 16), produced 1964-1966
• Bracelet 1035 (end piece no. 516), produced 1966-1972
• Bracelet 1039 (end piece no. 516), produced 1968-1971

The 1039 was fitted to the Omega Speedmaster Professional during the same period. These bracelets were not of high quality and were easily worn out and damaged. They are rare in today's second hand market, and when they surface they usually are more expensive than new ones.

Correct bracelets for the SM300: 1039 top, 1506 below. Notice how the Omega logo is placed all the way on the edge of the buckle on the 1506

On the inside of the buckle is the bracelet number, production year and the quarter of that year it was produced. Please note that on some bracelets the production year is missing.

Inside of a 1039 bracelet, produced in third quarter of 1971. Some bracelets do not have the production year. As I understand it, this is also viable bracelets.

Re-luming and Patina

A lot of the SM300s on the market have been re-lumed sometime in their lifetime. Many collectors shun these pieces and look upon this as a modification of the dial which should be original. Others find this ok, I guess it comes down to how damaged the dial is in the first place. If the damage to the lume is to such an extent that the value of the watch will increase with a re-lume I personally think it is ok. But be careful, usually a re-lume will devaluate the watch.

A re-lume is usually done with a modern lumination called "luminova". This shines quite differently from the the "tritium" lumination used in the sixties. Usually the old lume can be re-vitalized in direct sunlight or bright indoor lightning, and the difference is obvious, as illustrated below.

The difference between a re-lumed SM300 and one with the original lume. Both brightness and the greenish color are different.

Another thing we collectors look for is patina. Patina is a very attractive feature on a vintage watch, but there is a thin line between patina and wear/damage. A lot of sellers try to sell damaged dials as patinated dials. Patina should be evenly distributed, consistent in color and perceived as attractive. This goes for both the dial, hands and the bezel.

The patina should be light brown or beige in color. Be aware that some modern luminova can be that color and it is easy to be fooled from a nicely done re-lume. The only way to detect this is to see the brightness and the color of the lume in the dark as illustrated above. 

Correct SM300 with new hands. This illustrates the difference in lume and patina when replacing old hands.

Old Catalogs and Final Confirmation

As mentioned earlier, due dilligence and final purchase is something that is done with a certain amount of uncertainty given the way these watches were assembled by Omega. The final confirmation is usually old catalogs from the period where the actual watches from the different collections are pictured. These catalogs can also give confirmation to models thought to be frankenwatches, e.g. the SM300 with dauphine hands, illustrated below.

Omega catalog from 1964 with the rare SM300 with dauphine hands. A confirmation of the legitimacy of a previously thought frankenwatch.

A good catalog source is www.old-omegas.com.

This is more or less a summation of my findings and the most important things to heed when considering buying a vintage SM300. I think the watch is easier to buy than, say Omega Pie Pan Constellations. The rumor it has as one of the trickiest vintage purchases is somewhat undeserving. 

Happy hunting!