Case marks: marks in watch casesCopyright © Notice
Marks in watch cases can often tell us something about the history of the watch. They can sometimes tell us where and when the case or the watch was made, and who made it. But not always!
NAWCC Watch & Clock Bulletin article
Click this link to: DOWNLOAD
In Britain gold or silver watch cases should always have been hallmarked before sale - the laws on hallmarking were enacted long before watches were invented! Foreign made watch cases were no more exempt from the law than British made cases, but this was uneven before 1907. Apart from a short period between 1874 and 1887 when some, but not the majority, of foreign watch cases were hallmarked in the same way as British made watch cases, before 1907 most watches were imported either without hallmarks or with hallmarks from their country of origin.
This changed in 1907 when all imported gold and silver watch cases were ordered to be marked with British import hallmarks. From 1 June 1907 the assay offices were ordered to strike hallmarks on imported watch cases that were different from those struck on watch cases made in the UK. For instance the London Assay Office town mark for watch cases manufactured in Britain was a leopard's head, but the town mark used on imported watches became the sign of leo on a crossed back ground in an oval shield.
An easy way to distinguish a hallmark struck on an English made watch case from one on an imported watch case after 1 June 1907 is to look at the town mark, the symbol that shows which assay office carried out the assay and hallmarking, these were changed in 1907 for imported watch cases to distinguish them from watch cases made in the UK. If it is a silver watch case another clear indication is that the silver standard is given as .925 in an oval shield rather than by the traditional mark for sterling silver made in the UK of the lion passant, a walking lion with raised right forepaw.
You can read more about this on my page about British assay and hallmarking, or in my article published in the NAWCC Watch & Clock Bulletin as shown here. Articles in the NAWCC Bulletin are copyright and usually only available to NAWCC members. However, after a request from the the archivist of the Incorporation of Goldsmiths, who looks after the historical records of the Edinburgh and Glasgow Assay Offices, the editor of the NAWCC Bulletin has allowed the article to be made publicly available and it can now be downloaded by clicking on this this link: DOWNLOAD. My research has also been incorporated in the latest version of Bradbury's Book of Hallmarks, you can read about this at Bradbury's Book of Hallmarks.
This used to be a single page but it has grown so much that I have now split it into several pages as described below. You can click on the links to open each page in a separate tab, but don't forget to read the rest of this page too!
British import hallmarks
This picture shows London import hallmarks for silver used after 1 June 1907. The .925 in an oval shield was used instead of the lion passant on imported sterling silver.
Other British assay offices used different town marks for imported items, and marks on gold are different, as are different office date letters.
Click on this link to open my page about British import hallmarks
Swiss marks and hallmarks
A ladies head, a squirrel, bear, grouse or other various fauna like these are Swiss hallmarks, which were introduced in 1880.
In 1933 the bear for silver was changed to a duck.
The Swiss Federal Cross mark often indicates a Swiss patent.
Marks such as "Fine silver", 800, or 875 could also indicate a Swiss origin.
French names of parts such "cuivre", ancre" or "spiral" indicate a Swiss or French origin
Click on this link to open my page about
These marks, the walking lion of sterling silver, the leopard's head, and a date letter, are British hallmarks. British hallmarks like this were, and still are, applied to all gold and silver items made in Britain, and also to some imported watches before 1888.
Other symbols were used, such as an anchor to show the item was hallmarked in Birmingham, wheatsheaves for Chester, etc.
Click on this link to open my page about British Hallmarks
Sets of initials in shields like these are often sponsor's marks, part of a British hallmark. These marks tell us who sent the watch case to the assay office to be tested and hallmarked.
Click on this link to open the page about Sponsors Marks
Swiss Poinçons de Maître
In Switzerland in the 1920s a system of responsibility marks called poinçons de maître was introduced for watch cases, using a system of marks as shown below and code numbers. When stamped the XXX shown in the marks are replaced with a number that indicates the maker of the case.
Click on this link to open my page about Swiss Marks on Watch Cases
If none of this makes any sense to you, please feel free to ask me to help via my contact me page.
Watch Case Makers of England
by Philip Priestley
Watch Case Makers of England 1720-1920
If you are interested in watch cases and their makers, an invaluable reference is Philip Priestley's Book "Watch Case Makers of England 1720-1920." This book is only available from the author in Europe for £15 plus p&p. In America a friend of the author in North Carolina has some copies. This book contains the results of painstaking research into the case makers of London, Liverpool, Prescot, Chester, Coventry, Birminghman and other provincial towns, and has extensive appendices of hallmarks to enable you to identify the case maker, standard and year that your watch was assayed.
This book doesn't just cover watch case makers of England as its title suggests, but also includes the sponsor's marks of many watch importers and agents. At £15 it is an absolute bargain, and every serious collector of watches of the period covered should have a copy of it. You can contact Philip Priestley by email at . Philip has also written a book on watch case makers covering the earlier period of 1631 - 1720, and has new book on the watch case maker Dennison.
Silver Makers Marks Website
If you can't find your silver makers / sponsors mark on this page and you don't have Philip Priestley's Book, then a very useful web site with a large collection of silver marks is SilverMakersMarks.co.uk. If you do find your mark there, please let me know.
Watches with British Sponsor's Marks but No UK Hallmarks
Sometimes watches are seen with with British sponsor's marks, but no import marks. The reason for this is that in 1915, with the first World War (WW1) starting to impose a strain on the economy, the British Government imposed an ad valorem duty of 33.?% on imported luxuries including clocks and watches to conserve foreign currency reserves as part of the war effort. This meant that any watches imported into Britain, even if only for checking before subsequent export abroad, would be subject to this high rate of tax. Prior to this, many watches were imported to Britain before being re-exported to the Empire. Britain had large overseas territories at the time, which were a big market.
To avoid paying the tax on watches not destined for the British home market, many companies, including Rolex, George Stockwell, Rotherham and Sons, Rendells, and Baume & Co., either set up Swiss offices, or made arrangements to export watches direct from Switzerland to the British Empire, bypassing Britain and avoiding the high import duty.
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Before 1886 German states were independent and Sovereign. Each state, city state or city had their own hallmarks or Feingehaltstempel for gold and silver.
Halbmond und Reichskrone
After the unification of the 39 sovereign German states into the German Empire in 1871, the foundation of modern Germany, country wide laws began to be introduced. From 1886 a single mark of a crescent or half moon and imperial crown (Halbmond und Reichskrone) was used by all German states .
An old German quantification of silver purity was based on sixteenth parts called "lots", e.g. 14 lots was 14 parts out of 16 pure silver, equal to 0.875 or 87.5% silver. A minimum standard purity for silver of 800 parts per thousand (80% or .800) had been established in 1884.
These marks were stamped on imported items as well as German made items, so the half moon and crown can be seen alongside e.g. Swiss hallmarks such as the bear or grouse on Swiss items imported into Germany.
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Since the Middle Ages over 5,000 different punches have been used in France to hallmark silver and gold. The huge number of different punches and the the complexity of the French administration of hallmarking means that this is a massive subject that requires an encyclopedia to cover it, which I am not going to attempt here.
One French mark that comes up quite often on Swiss watches is that of a swan or cygne. Even this mark is rather difficult to pin down. It was used for items that were not hallmarked in France in the normal way, and so was principally used on imported items, such as Swiss watches imported into France. It shows that the item meets the minimum French legal standard, which for silver was 800 millièmes or 800 parts per thousand (80% silver).
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In Russia before the revolution fineness was expressed in zolotniks, which was derived from the Russian for gold, zoloto, and which was also the name of a gold coin. There were 96 zolotos to a pound and zolotniks are a ratio of this, e.g. 56 zolotniks = 56/96 = 0.583, the fineness of 14 carat gold, and 84 zolotniks = 84/96 = 0.875 for silver.
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Poland appears to have started hallmarking gold and silver in 1920. A male head with a helmet was used for gold (zloto) and a female head covered with a scarf was used for silver (srebro). Three standards of gold were recognised, 960, 750 and 583. Three standards of silver were recognised, 940, 875 and 800.
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Who Made My Watch?Copyright © Notice
The question I am most often asked is "Who made my watch?" This question usually occurs because the watch has no visible makers name, and the answer is not as straightforward as you might think. There are various reasons why an old watch does not carry a maker's name, but today people are so used to seeing brand names on everything, especially watches, that they expect to see one. It has not always been the case that everything had a brand name, or that an unnamed watch was made by a well-known company who have hidden their name out of sight for some mysterious reason.
When it comes to vintage watches, by which I mean watches made before WW2, English watches often carry the name of the retailer, American watches usually carry the name of the manufacturer, and Swiss watches often carry no name at all or simply "Swiss made". Of course this is rather a broad generalisation, because some English and Swiss watches, usually the best quality, did carry the manufacturer's name. And some Swiss watches, usually of the worst quality, carried fake names, pretending to be of English or American manufacture.
English watches were almost all made entirely using craft methods, hand tools and simple hand powered machines, and the system of "putting out". Each part was made or finished by an individual craftsman working in his own home or small workshop, often working for several different customers. In the nineteenth century the movements often began "in the rough" as "frames", consisting of the plates and a few parts of the mechanism such as the spring barrel, fusee and train wheels. In the nineteenth century many if not most of these frames were made at Prescot in Lancashire, many by John Wycherley, an English pioneer of mass production.
The frames were sent from Prescot to the traditional watchmaking centres of London, Coventry and Birmingham to be "finished" into working movements and then fitted with dials, hands and cases. Sometimes this was done by watch manufacturer who directly employed journeymen and apprentices to do the finishing, but many watches were made by the process of "putting out" - sending the part finished watch to various specialists working in their own homes or small workshops to have each stage of the work completed. Because the watch manufacturer, who was really just the controller of the process and could be an individual or small small company, did not produce enough watches for their names to become known, it was not worth going to the expense of having it engraved on the plate, a craft process that was done by hand by a skilled craftsman and therefore not cheap.
Sometimes the name of the retailer who had ordered the watch to be made was engraved on the plates as if they were in fact the manufacturer, although ordering it was their only involvement in its actual manufacture. The retailer would be someone well known and trusted by his customers, whereas they would never have heard of the many names of the small controllers who perhaps might have been thought of as the manufacturer, although their part of the process was more pulling everything together than actually making all the parts.
Some of the best known London makers did establish a sufficient reputation for their name to be valuable and be put onto the movement or dial, but many of the hundreds, or even thousands, of small "makers" are unknown. Even the best English makers did not always put their name on their work, the retailers preferring that if any name appeared it should be theirs. Appearing in 1887 before a Select Committee considering amendments to the 1862 Merchandise Marks Act, Mr Joseph Usher, of the famous company Usher and Cole, said that ... it is very seldom that our names appear on the watches that we make.
Towards the end of the nineteenth century a few English watch manufacturers, the best known being Rotherhams of Coventry, introduced mechanical methods of manufacture and produced enough watches to be known by name, but their production quantities were small compared to the American factories, and they suffered from too little investment too late, being unable to keep up with changing fashions and finally swept away by Swiss imports and the wristwatch.
So who did make my English watch?
If you have an English watch that does have a name on the dial or engraved on the plates and it is not the name of a well known watchmaker that can be easily researched, then it is likely to be the name of the retailer. Many retailers called themselves "watchmakers" although they were not watch manufacturers and did not actually ‘make’ the watches that they sold. The term watchmaker undoubtedly originally meant someone who made watches, but by the eighteenth century the trade of watchmaking had been divided into many separate branches and no one person made a whole watch. So people who made parts for or repaired watches called themselves watchmakers, and then also those who simply serviced watches, and finally jewellers who ordered watches from the manufacturers started calling themselves watchmakers.
It is often easy to find out who was responsible for making the watch case, because for hallmarking purposes a sponsor's mark had to entered at the assay office and each case punched with this mark before it was submitted for hallmarking. Sometimes this can lead to the watch manufacturer if they were large enough to have a case making department, but often it only gives you the name of an independent watch case maker, working on his own account for any watch manufacturer or finisher who cared to place an order with him.
Sometimes it is possible to discover who made the "frame" or rough movement by looking for initials on the bottom plate, the plate underneath the dial. An example of these are the initials JW for John Wycherley of Prescot, an English pioneer of mass produced frames. Click this link to see a watch with a Wycherley frame. If you have the watch serviced, which you certainly should do if you intend to use it, then ask your watchmaker to take a photograph of the plate for you.
If there is no name on the dial or engraved on the plates, then the watch was "made" by one of the small finishers whose name was not sufficiently well known or celebrated to be worth the expense of engraving it onto the plate, and the retailer didn't have his name engraved on the plates, probably for reasons of cost.
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America had no traditional craft watchmaking industry, where watches were manufactured largely by hand using simple tools and craft methods. There may have been a few individual American watchmakers who worked in this way, but very few of their watches survive. They would have imported at least some of parts, such as the springs and dials, from England or Switzerland, and probably most were imported as complete watches, or complete movements that were cased in America, which the American watchmakers then put their names on.
Watches began to be manufactured in large numbers in America in the 1850s in large integrated factories by companies such as that set up by Dennison, Howard and Davis that became the American Watch Company of Waltham, and the spin-offs and rivals that were set up in competition such as Elgin, Howard, Hampden and the Springfield Illinois Watch Company. These factories used what became known as the "American system" of watch manufacture, interchangeable parts mass produced on purpose made machinery, and assembled by mainly semi-skilled labour. Each factory produced watches by their thousands, and the names of the factories stamped onto the movements became well known in the trade and to customers. The factory name became a powerful marketing tool.
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The most frequently encountered watches with no name on them were made in Switzerland, but why was this?
Switzerland made more watches than anyone else, and carried on making them in greater and greater numbers after first the English and then American watchmaking industries faded away. Many of these watches were made before the importance of having a "brand" was dreamt up by clever marketing executives. Often these watches have no name on them at all, or the name of the retailer who sold the watch.
Watchmaking in Switzerland was an important national industry. In Geneva there were small individual manufacturers who could trace their roots back to the middle ages and the beginning of watchmaking, but in Neuchâtel, and the Jura mountains, in places such as Le Locle and La Chaux-de-Fonds, the Vallée de Joux, where the vast majority of Swiss watch were made in the nineteenth and twentieth century, almost everyone was involved in some way in watchmaking in some way, but no one actually made in one workshop all the separate parts and assembled a complete watch. The whole area was devoted to watchmaking, and this is why watches from this region were rarely marked with an individual maker's name. They were the product of a collaborative effort involving many individual companies and specialists.
Origins of the Swiss watch industry
Some old-established companies, such as Vacheron Constantin and Patek Philippe, were (and these two companies still are) "manufactures", firms that made most or all of the parts of the watch movement in-house, who established a reputation and put their name clearly on the finished watch. Patek-Philippe's reputation was helped somewhat when Prince Albert purchased Patek Philippe watches for himself and Queen Victoria at London's Crystal Palace Exhibition in 1851. Such companies were mainly based in the traditional Swiss watchmaking centre of Geneva, where watches of the finest quality had been made for centuries.
However, the named "haute horology" (high, or top end, watch manufacturers) became a minority of Swiss manufacturers after the creation of the watch industry in the Jura region in the eighteenth century, when Daniel Jean-Richard showed farmers in the Jura mountains how to supplement their income during the long winter months when they were snowed in by making watch parts. After that revolution most Swiss watches were made by a style of manufacturing called établissage. Material was provided to workers operating in their own homes or small workshops, and then the finished components were collected and assembled into complete watches in a workshop or factory établissement". The man in charge of the whole process was called the établisseur.
There were of course exceptions to this rule. One of the most notable was Longines, who set up an integrated factory in the nineteenth century to produce complete watches, another was Stauffer, Son & Co. But these were the exception, and many Jura watches were assembled from components by small établisseurs.
When Swiss exports to America fell off dramatically in the 1870s as the Americans factories ramped up production, the Swiss reacted and mechanised, but in the main they didn't integrate into single factories making complete watches. Makers of bare movements or ébauches set up in larger factories, but many small specialist companies continued to thrive in the centres of watchmaking in the Jura; La Chaux-de-Fonds and Le Locle and the areas around. Dial were made by specialist dial makers, hands by hand makers, cases by case maker, and so on, preserving the division of specialisation in these areas that allowed the Swiss to overcome the challenge from America.
Although the basic movement, the ébauche, looks like such a complicated and delicate thing that it must be very difficult to make, the Americans had shown in the 1850s that the individual parts could be turned out very cheaply in their thousands by purpose built machinery. The Swiss had adopted this method of manufacturing and henceforth most Swiss ébauches were made by huge producers such as the Fabrique d'horlogerie de Fontainemelon, the first Swiss ébauche factory, which was set up at Fontainemelon between La Chaux-de-Fonds and Neuchâtel, or the big factories in Grenchen such as A. Schild, and Schild Frères which gave rise to Eterna and Eta, who supplied them to the many hundreds, or even thousands, of établisseurs, who combined them with cases, dials and hands into complete watches.
Usually no one put their name onto such watches as manufacturer, and at the time the retailers didn't want a maker's name on the dial, certainly not if it was a Swiss watch to be sold in Britain. English made watches enjoyed a high reputation with the public, and retailers felt that having an unknown foreign sounding name on the watch would make it more difficult to sell. So they ordered watches with plain dials and had their own name put on it: Harrods in London, Hamilton and Inches in Edinburgh, and the name of the jeweller in every city and town in between. Customers trusted their local jeweller and were happy to buy a watch with their name on the dial, and their reputation standing behind it.
To a large extent, the Swiss watch industry (especially outside Geneva) in the nineteenth and first half of the twentieth century was one giant enterprise, the end product being "Swiss" watches. Many towns in the Jura mountains were almost entirely dedicated to the production of watch parts and the assembly of these into finished watches. In Das Kapital Karl Marx described the very high division of labour in the Swiss watch industry and said that La Chaux-de-Fonds was a "huge factory-town" such was the extent that it seemed every part of the town was involved in the industry of making watches. Individual companies competed against each other to produce parts of the watch better or cheaper, producing economies of production due to specialisation and division of labour. These individual parts were assembled into complete watches; watches that didn't have a "maker" as such, which is why there is no visible maker's name on these watches, although often the trademark of the maker of the ébauche can be found on the bottom plate under the dial so that spare parts could be sourced. From about 1880 international agreements dictated that the place of origin of goods should be indicated and this resulted in a discreet "Swiss made" at the bottom of the dial.
The rise of "brands"
Hans Wilsdorf was one of the first people to recognise the power of a brand in selling watches and created the Rolex name in 1908, but it wasn't until the mid-1920s that Wilsdorf succeeded in persuading English retailers to accept watches with the Rolex name instead of their own on the dial. (Ironically Rolex weren't a manufacture, they bought their movements from a firm called Aegler, who they eventually took over - there is more about this on my Rolex page.) Where Rolex led others followed and watch brands were created or promoted, gradually at first with a brand still meaning something: that the watch had been at least conceived, assembled and tested by the named company. But as the twentieth century progressed the cult of the "brand", created by advertising agencies, meant that everything had to have a "Name" associated with it, and by the 1970s brands were being created from thin air and watches were produced with this name on them by anonymous Swiss, or even far-East, assemblers.
However, often quite a lot about the history of a vintage watch can often be discovered from marks on the case and movement, especially if it has a silver or gold case and was imported and sold in the UK, because then by law it should be assayed and hallmarked, although this law was only consistently applied after June 1907. For help reading the hallmarks in watch cases, see my Case marks page.
Sometimes the maker of the ébauche can be identified from the shape of the parts of the movement or a trademark, which is often concealed under the dial. The makers of ébauches also wanted to be able to sell movements to as many different établisseurs as possible, who each wouldn't want the same movements in their watches as anyone else. To this end, ébauche makers even made exactly the same movement with different shaped plates so that they looked different. For help with identifying an unnamed watch movement, refer to my Movements page.
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Numbers on movements and cases
Numbers stamped or neatly engraved into a watch case or on a movement are most often the manufacturer's serial numbers, but in some cases they are references to a patent or registered design which can tell us something about the watch. References to patents or registered designs usually have some text in addition to the number, and the numbers are fairly short. Long strings of numbers on their own are usually serial numbers.
Quite often there are little scratched marks that have obviously been made by hand inside the back of a watch case. These are watch repairer's or watchmaker's marks from when the watch has been serviced over the years, they help them to identify their work if a customer brings the watch back later. Sometimes they include a date, which shows when the watch was serviced, but others are codes and to find out exactly what they meant you would need to ask the watchmaker.
Watch movement serial number
Watch case serial number
Watch movements and cases often have a long number like the 60749 on the barrel bridge of the fine 17 jewel Electa movement from 1915, or 3130633 in the silver Borgel watch case shown here. These are "serial numbers".
Serial numbers were usually allocated in sequence, incremented in ones, and were used to keep track of production. This was useful when a watch repairer needed a spare part, allowing the correct item to be supplied, or in case some faulty components or material were used in a batch or items which later needed to be recalled. Serial numbers don't in themselves contain any information and are only useful if you can identify first the watch manufacturer, if the manufacturer is still in existence, and then if they still have access to their old records.
Some manufacturers serial numbers are known and published in reference works or on the web - but to use these you need first to know who the manufacturer was; you can't work backwards from a serial number to a manufacturer.
You shouldn't even assume that it is possible to infer anything from the magnitude of a number, for instance a newly formed company might like to give the impression that they had made a lot of watches, so they might arbitrarily started their numbering at, say, 700,000, implying that they had made this number of watches when in fact watch number 700,001 might be the first one they made.
It is not possible to identify the maker of a watch or watch case just from serial numbers stamped on the movement or case, because serial numbers are just what the name says they are - numbers - every manufacturer can easily have used the same numbers at different times.
For instance, take a completely random number such as 1234567 - one million, two hundred and thirty four thousand, five hundred and sixty seven. Longines made a watch with this serial number in 1900, and IWC made a watch movement with exactly the same serial number in 1951.
There is nothing spooky about this numerical "coincidence", it just shows that by the year 1900 Longines had already made over a million watches, whereas it took IWC until 1938 to make their first million watches, and until 1951 to make movement number 1,234,567, by which time Longines were in the eight millions.
So you can see that knowing just the movement or case serial number doesn't help to identify the manufacturer.
Poinçons de Maître
In the 1920s a system of Poinçon de Maître (literally "Punch of the Master" but usually translated in this context as Collective Responsibility Mark) was introduced for Swiss watch case makers, to provide traceability back to the actual maker of the watch case. This required all precious metal watch cases made in Switzerland to carry a mark to identify the case maker.
Poinçons de Maître
Watchmakers didn't usually want the name of the case maker, which was normally a separate company, appearing in the back of their watches, so a system of marks and code numbers was devised by the Swiss watch case manufacturers, with different symbols representing the different case making regions of Switzerland. The six types of marks are shown in the picture. These are called collective responsibility marks because each one was used by more than one member of the association. When stamped the XXX shown in the marks are replaced with a number that indicates the maker of the case.
These marks are usually seen in gold, platinum or palladium cases. Although there was provision made by the case makers association for silver cases to be marked, these are rarely if ever seen.
You can read more about this system and how to interpret the marks at Swiss Poinçons de Maître.
Patents and registered designs
Numbers referring to patents or registered designs are usually shorter than serial numbers, and have something in addition to the numbers, e.g. patents may have the word patent or its abbreviation pat. An example is the wording "U.S. Pat. 24 May 1904" seen on otherwise unidentified movements, which is a reference to a patent granted to Henri Sandoz of Tavannes/Cyma for a negative set stem winding and setting mechanism (keyless work).
In Swiss/French "brevet d'invention" means the same as patent, this is often abbreviated to simply brevet or brev. The Swiss Federal Cross symbol also usually indicates a Swiss patent.
A Registered Design may be indicated by the English abbreviation "RD" or the Swiss/French "Modèle deposé". Modèle means design, deposé means to file, lodge or deposit. Sometimes these are accompanied with "demandé", which means requested.
One modèle deposé reference that occurs frequently in the cases of early Swiss wristwatches with fixed wire lugs, like the one shown in the picture here, and in the picture of the watch case above where it can be seen next to the trademark of François Borgel is No. 9845. You can read about this at Modèle deposé 9845.
- On its own usually signifies that a Patent has been granted, a number indicates the patent number.
- Brevet Deposé
- Registered Patent - a request for a patent has been registered.
- Brevet Demandé
- Patent Requested. Sometimes abbreviated to Brevet Dem. or just Br. Dem.
- Modèle Déposé
- Registered Design. Sometimes abbreviated to Mod. Dep. or Déposé.
Brevet Deposé and Brevet Demandé both mean essentially the same thing, that a patent has been applied for, but of course there is no guarantee that an application will result in the grant of a patent and neither are official terms. Brevet Deposé sounds more convincing, like the rather presumptive "Patent Pending", which also has no official status.
Modèle Déposé does actually mean something, the design has been officially recorded and "registered", the same as a British "Registered Design". This doesn't convey protection in the same way that a patent does, but it forms an official record of who first produced the design and can be used in cases of copyright dispute.
Sometimes a patent number isn't given. There are various reasons for this, which revolve around whether a patent has actually been granted, and whether it is actually relevant. Manufacturers liked to allude to patents in order to give the idea that their design included some clever feature, or that it was protected from copying by a patent. Sometimes this was just sheer bluff.