A hallmark is an official mark or series of marks struck on items made of precious metals—platinum, gold, silver and in some nations, palladium. In a more general sense, the term hallmark can also be used to refer to any distinguishing characteristic or trait.
General overview 
Historically, hallmarks were applied by a trusted party: the 'guardians of the craft' or nowadays by an assay office. Hallmarks are a guarantee of certain purity or fineness of the metal as determined by formal metal (assay) testing.
Hallmarks are often confused with "trademarks" or "maker's mark". Hallmarks are not the mark of a manufacturer to distinguish his products from other manufacturers’ products, which is the function of trademarks or makers' marks. To be a true hallmark, it must be the guarantee of an independent body or authority that the contents are as marked. Thus, a stamp of '925' by itself is not, strictly speaking, a hallmark, but is rather an unattested fineness mark.
Prerequisites to hallmarking 
Notwithstanding the hallmarking systems themselves, many nations require, as a prerequisite to official hallmarking, that the maker or sponsor itself mark upon the item a responsibility mark and a claim of fineness. Responsibility marks are also required in the U.S. if metal fineness is claimed even though there is no official hallmarking scheme in that country. Nevertheless, in nations with an official hallmarking scheme, the hallmark is only applied after the item has been assayed to determine that its purity conforms not only to the standards set down by the law but also with the maker’s claims as to metallurgical content.
In some nations, such as the UK, the hallmark is made up of several elements including: a mark denoting the type of metal, the maker/sponsor's mark and the year of the marking. In England, the year of marking commences on May 19, the Feast Day of Saint Dunstan, patron saint of gold- and silversmiths. In other nations, such as Poland, the hallmark is a single mark indicating metal and fineness, augmented by a responsibility mark (known as a sponsor's mark in the UK). Among a group of nations which are signatories to an international convention known as the Vienna Convention on the Control of the Fineness and the Hallmarking of Precious Metal Objects, additional, optional, yet official marks may also be struck by the assay office. These have the effect of easing import obligations among and between the member states. Signatory countries have a single representative hallmark which would be struck next to the Convention mark which represents the metal and fineness.
History of hallmarking 
Ancient Byzantine hallmarks 
The control or inspection of precious metals was an ancient concept of examination and marking, by means of inspection stamps (punch marks). The use of hallmarks, at first, on silver has a long history dating back to the 4th century AD and represents the oldest known form of consumer protection. A series or system of five marks has been found on Byzantine silver dating from this period though their interpretation is still not completely resolved.
Hallmarking in the Late Middle Ages 
However, from the Late Middle Ages, hallmarking was administered by local governments through authorized assayers. These assayers examined precious metal goods, under the auspices of the state, before the good could be offered for public sale. By the age of the Craft Guilds, the authorized examiner’s mark was the “master’s mark” which consisted frequently of his initials and/or the coat of arms of the goldsmith or silversmith. At one time, there was no distinction among silversmiths and goldsmiths who were all referred to as "orfèvres", the French word for goldsmith. The Master Craftsman was responsible for the quality of the work that left his atelier or workshop, regardless of who made the item. Hence the responsibility mark is still known today in French as le poinçon de maître literally "the maker's punch." In this period, fineness was more or less standardized in the major European nations (writ: France and England) at 20 karats for gold and 12 to 13 lots (75% to 81%) for silver, but the standards could only be partly enforced owing to the lack of precise analytical tools and techniques.
Hallmarking is Europe's earliest form of consumer protection. Modern hallmarking in Europe appears first in France, with the Goldsmiths Statute of 1260 promulgated under Etienne Boileau, Provost of Paris, for King Louis IX. A standard for silver was thus established. In 1275, King Philip III prescribed, by royal decree, the mark for use on silver works, along with specific punches for each community's smiths. In 1313, his successor, Philippe IV "the Fair" expanded the use of hallmarks to gold works.
In 1300 King Edward I of England enacted a statute requiring that all silver articles must meet the sterling silver standard (92.5% pure silver) and must be assayed in this regard by 'guardians of the craft' who would then mark the item with a leopard's head. In 1327 King Edward III of England granted a charter to the Worshipful Company of Goldsmiths (more commonly known as the Goldsmiths' Company), marking the beginning of the Company's formal existence. This entity was headquartered in London at Goldsmiths' Hall from whence the English term "hallmark" is derived. (In the UK the use of the term "hallmark" was first recorded in this sense in 1721 and in the more general sense as a "mark of quality" in 1864.)
In 1424, the French Archbishop Jean de Brogny, after having consulted with a council of eight Masters Goldsmiths from Geneva, enacted a regulation on the purity and hallmarking of silver objects following the French standards for application in Geneva. Although gold was certainly used for articles, the regulation was silent on gold standards and its hallmarking. (Today in Switzerland, only precious metal watch cases must be hallmarked. Perhaps this attests to the significance of watches to the Swiss economy. The hallmarking of other items including silverware and jewelry is optional.)
Augmentations in France and England 
- In 1355, individual maker marks were introduced in France, which concept was later mirrored in England in 1363, adding accountability to the two systems.
- In 1427, the date letter system was established in France, allowing the accurate dating of any hallmarked piece.
- In 1478, the Assay Office was established in Goldsmiths' Hall. At this time, the date letter system was introduced in England.
- In 1697, a higher standard of silver, known as the Britannia standard (95.8% silver) was made compulsory in Great Britain to protect the new coinage which was being melted down by silversmiths for the silver. The Sterling standard was restored in 1720.
Modern hallmarks 
In the modern world, in an attempt at standardizing the legislation on the inspection of precious metals and to facilitate international trade, in 1973 a core group of European nations signed the Vienna Convention on the Control of the Fineness and the Hallmarking of Precious Metal Objects. Those articles, which are assayed and found to be in conformity by the qualifying office of a signatory country, receive a mark, known as the Common Control Mark (CCM), attesting to the material's fineness. The multi-tiered motif of the CCM is the balance scales, superimposed, for gold, on two intersecting circles; for platinum, a diamond shape and for silver a mark in the shape of the Latin letter "M".
This mark is recognized in all the other contracting states, including: Austria, Cyprus, the Czech Republic, Denmark, Finland, Great Britain, Hungary, Ireland, Israel, Latvia, Lithuania, the Netherlands, Norway, Poland, Portugal, Sweden, Switzerland and Ukraine (see links below). Other nations monitor the activities of the Convention and may apply for membership.
Complete international hallmarking has been plagued by difficulties, because even amongst countries which have implemented hallmarking, standards and enforcement vary considerably, making it difficult for one country to accept another's hallmarking as equivalent to its own. Many nations monitor the Vienna system and procedures are in place to allow additional nations to join the Vienna Convention. Similarly, with the consent all the current member states, the terms of the convention may be amended.
The most significant item currently up for debate is the recognition of palladium as a precious metal. Some member nations recognize palladium as a precious metal while others do not. (See list of nations below).
Polish - Poland 
Hallmarks for gold, palladium, platinum and silver from Poland. Official Polish hallmarks between 1963–1986
French - France 
Official French Hallmarks used between 1798 and 1972 for gold and silver.
French mark head of horse for jewellery and watches from 18k gold made in the French provinces between 1838-1919
The Hallmarking Act 1973 made Britain a member of the Vienna Convention as well as introducing marking for platinum, a recognised metal under the Convention. All four remaining assay offices finally adopted the same date letter sequences. The latest changes in 1999 were made to the UK hallmarking system to bring the system closer into line with the European Union (EU). Note: that under this latest enactment, the date letter is no longer a compulsory part of the hallmark.
As it now stands, the compulsory part of the UK hallmark consists of the sponsor or maker's mark, the assay office mark, and the standard of fineness (in this case silver, 925 parts in 1000).
These are shown in the top of the two example hallmarks. The bottom example shows the extra marks that can also be struck, the lion passant, indicating Sterling silver, the date mark (lowercase a for '2000'), and in this example, the 'Millennium mark', which was only available for the years 1999 and 2000. The bottom example bears the Yorkshire rose mark for the Sheffield Assay Office.
The Hallmarking Act was amended in July 2009 to include palladium from January 2010
Although hallmarking in the Swiss territories dates back to Geneva in the 15th century there was no uniform system of hallmarking in Switzerland until 1881. Before that time, hallmarking was undertaken at the local level by the Swiss cantons. With the introduction of the Swiss system of hallmarking in 1881, there was uniformity throughout the nation. Distinctive symbol: Biel / Bienne B
Basel * Chiasso T Geneva G La Chaux-de-Fonds C Le Noirmont J Zurich Z
These symbols will appear in place of the "X" on the ear of the St. Bernard dog. Under the current law, on all gold, silver, platinum or palladium watches cases made in Switzerland or imported into Switzerland, (Fr.) there shall be affixed, near the Maker's Responsibility Mark and his indication of purity, the official Hallmark, the head of a Saint-Bernard dog (illustrated below). Only precious metal watch cases must be hallmarked. Swiss hallmarking for other articles such as jewelry and cutlery is optional.
In addition to the Swiss hallmark, all precious metal goods may be stamped with the Common Control Mark of the Vienna Convention.
The Dutch, who are members of the International hallmarking Convention, have been striking hallmarks since at least 1814. Like many other nations, the Dutch require the registration and use of Responsibility Marks, however, perhaps somewhat unique, the Dutch publish a book entitled "Netherlands' Responsibility Marks since 1797" (in three volumes and in the English language) illustrating all the responsibility marks registered there since that time. This is significant since producers that exported precious metal good to the Netherlands would have been required to register their marks.
The Dutch government markets their assay services/office as the "Jewellery Gateway in and to Europe." The Netherlands' hallmarks are also recognized in other E.U. countries and thus can be sold in Austria, France, Ireland, Portugal, Spain and the United Kingdom without further testing. The Netherlands' hallmarks are also recognized in Belgium, Denmark, Finland and Sweden, which have voluntary hallmarking systems.
One of the 2 Dutch assay offices is located in Gouda between the Amsterdam and Rotterdam Airports. The other one is located in Joure, called Edelmetaal Waarborg Nederland b.v.The Dutch recognize platinum, gold, silver and palladium as precious metals.
Marking techniques 
Traditionally, the hallmarks are 'struck' using steel punches. Punches are made in different sizes, suitable for tiny pieces of jewelry to large silver platters. Punches are made in straight shank or ring shank, the former for normal punching with a hammer, and the latter used with a press to mark rings. The problem with traditional punching is that the process of punching displaces metal, causing some distortion of the article being marked. This means that re-finishing of the article is required after hallmarking. For this reason, and that off-cuts from sprues are often used for assay, many articles are sent unfinished to the assay office for assay and hallmarking.
Laser marking 
A new method of marking using lasers is now available, which is especially valuable for delicate items and hollowware, which would be damaged or distorted by the punching process. Laser marking also means that finished articles do not need to be re-finished. Laser marking works by using high power lasers to evaporate material from the metal surface. Two methods exist, 2D and 3D laser marking. 2D laser marking burns the outline of the hallmarks into the object, while 3D laser marking better simulates the marks made by punching.
Methods of assay 
Precious metal items of art or jewelry are frequently hallmarked (depending upon the requirements of the laws of either the place of manufacture or the place of import). Where required to be hallmarked, semi-finished precious metal items of art or jewelry pass through the official testing channels where they are analyzed or assayed for precious metal content. While different nations permit a variety of legally acceptable finenesses, the assayer is actually testing to determine that the fineness of the product conforms with the statement or claim of fineness that the maker has claimed (usually by stamping a number such as 750 for 18k gold) on the item. In the past the assay was conducted by using the touchstone method but currently (most often) it is done using X-ray Fluorescence (XRF). XRF is used because this method is more exacting than the touchstone test. The most exact method of assay is known as fire assay or cupellation. This method is better suited for the assay of bullion and gold stocks rather than works or art or jewelry because it is a completely destructive method.
The age-old touchstone method is particularly suited to the testing of very valuable pieces, for which sampling by destructive means, such as scraping, cutting or drilling is unacceptable. A rubbing of the item is made on a special stone, treated with acids and the resulting color compared to references. Differences in precious metal content as small as 10 to 20 parts per thousand can often be established with confidence by the test. It is not indicated for use with white gold, for example, since the color variation among white gold alloys is almost imperceptible..
X-ray fluorescence 
The modern X-ray fluorescence is also a non-destructive technique that is suitable for normal assaying requirements. It typically has an accuracy of 2-5 parts per thousand and is well-suited to the relatively flat and large surfaces. It is a quick technique taking about three minutes, and the results can be automatically printed out by the computer. It also measures the content of the other alloying metals present. It is not indicated, however, for articles with chemical surface treatment or electroplating.
Fire assay 
The most elaborate, but totally destructive, assay method is the fire assay, or cupellation. As applied to gold bearing metallics, as in hallmark assaying, it is also known as cupellation and can have an accuracy of 1 part in 10,000. In this process the article is melted, the alloys separated and constituents weighed. Since this method is totally destructive, when this method is employed for the assay of jewelry, it is done under the guise of random or selective sampling. For example if a single manufacturer deposits a lot of rings or watch cases, while most are assayed using the non-destructive methods a few pieces from the lot are randomly selected for fire assay.
Other methods 
There are methods of assay noted above which are more properly suited for finished goods while other methods are suitable for use on raw materials before artistic workmanship has begun. Raw precious metals (bullion or metal stock) are assayed by the following methods: silver is assayed by titration, gold is assayed by cupellation and platinum is assayed by ICP OES spectrometry.
See also 
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- Benson, P.L. & Gilmore, R.S. Non-Destructive Imaging Of Worn-off Hallmarks and Engravings From Metal Objects of Art Using Scanning Acoustic Microscopy, November 15, 2004 citing Dodd, E.C. & Kent, J.P.C. Byzantine Silver Stamps Dumbarton Oaks Studies, 7 ,Washington, 1961. Compare “Historisches Lexikon der Schweiz" (in German, e.g. there is evidence of silver bars marked under authority of the Emperor Augustinian around 350 A.D.).
- "Online Etymology Dictionary". Etymonline.com. Retrieved 2011-12-11.
- Babel, Antony, Histoire Corporative de l’horlogerie, de l’orfèvrerie Genève, 1916, at page 4.
- Swiss Hallmarks on Gold Watchcases, NAWCC Bulletin, ISSN 1527-1609 , Dec. 2005, vol. 47, no6, pp. 686-699 [14 page(s)]; Eine Deutsche Übersetzung: Sehen Sie auch, Schweizer Punzen auf Uhrgehäusen in Gold, Chronométrophilia, Été/Sommer 2007, No. 61, an Seite 90.
- Swiss Customs
- Vienna Convention on the Control of the Fineness and the Hallmarking of Precious Metal Objects
- London Assay Office
- Organ, R. M. (2010). "Palladium Hallmarking in the UK". Platinum Metals Review 54 (1): 51. doi:10.1595/003214010X482375.
- Olivia Lowe (2011-11-30). "The Goldsmiths' Company - Assay Office". Thegoldsmiths.co.uk. Retrieved 2011-12-11.