Sumptuary Arts
Silversmithing and goldsmithing are equivalent terms and both refer to the art of create pieces in silver and gold. As an art made with precious metals, silversmithing has been a highly valued art throughout history. To give us an idea of its value, pieces of silversmithing had much more value in the Modern Age than any painting or sculpture. This paradigm changed with the birth of History of Art in the eighteenth century, because the discipline decided to elevate techniques as paint or sculpt to the category of “Fine Arts” and to relegate silversmithing —along with other appreciated disciplines such as tapestry, porcelain, enamel, ivory, etc.— to the category of “Decorative Arts”. This distinction is paradoxical, considering that the function of a painting or a sculpture is basically to “decorate”, while arts such as silversmithing, ceramics or glassware serve a useful purpose in people’s daily lives —tableware, accessories, dresser items, etc.— Because of the richness of their materials and historical appreciation, historians of such disciplines often prefer the term “Sumptuary Arts”.
Authenticate the quality and purity of materials
Both gold and silver are noble metals, very rare in the earth crust, and very valuable. Because of that, the art of silversmithing always had the need to certificate and authenticate its quality and purity to avoid deceit and fraud. That led the European governments from the late Middle Ages —in Spain by a Royal Pragmatic of the Catholic Monarchs— to establish a marking system to ensure the authenticity and legitimacy of the material. One of the most exciting features of the study of the art of silversmithing is to interpret these marks, which are specific to each silversmith and territory.
Marks of quality
One of these marks, the mark of quality of the material, is still obligatory. If you look at your silver jewellery, if the piece is sterling silver, you must see small numbers engraved somewhere in the surface. In the case of silver, you should look for a “925”. This means that the material has a purity of 92.5% or 925 thousandths of pure silver per gram of material —the rest being usually copper—. This is known as sterling silver or in Spanish, plata de 1ª ley —“silver of first law”—. Pure silver cannot be used in jewellery because it is too soft and needs to be alloyed with another material. The plata de 2ª ley —“silver of second law”— has 800 thousandths of pure silver, or a purity of 80%.
Gold
Gold, besides being scarcer and more expensive, is softer than silver and needs to be alloyed with a higher percentage of another material. Gold “of first law” —18 carat— has 750 thousandths of pure gold for each gram of material —the rest being usually copper and silver—, which means a purity of 75%. That is why gold jewellery s engraved with the number “750”. Above that, there is fine or pure gold —24 carat— which is too soft to be used in jewellery. Below that, Gold “of second law” —14 carat— is marked with the number “580”, meaning a purity of 58%. It is also convenient to distinguish that when we talk about “karats” we can refer to two different units of measurement, karat (k) with a k —which comes from the English word karat—, the unit of measurement of the purity of gold; and carat (ct) with a q, the unit of mass of precious stones –for example, a carat would be 0.20 grams of diamond—.
Other marks
If we examine historical pieces, we can find four other marks. The first one is the mark of the silversmith and is equivalent to his signature, usually consisting of an initial and his surname. The other three marks refer to the quality controls of the silver. The mark of the marker or assayer was stamped by the silversmith designated by each town council to ensure the quality of the material used by the silversmiths. The assayer conducted a test known as “assay” to determine if a piece was made of sterling silver or fine gold, and if it was not, it was destroyed. If it was suitable for sale, the assayer stamped his personal mark —usually initial and surname— and the mark of the city, a particular emblem of each town. Some cities maintained a fixed mark —such as the Tower of Hercules in Coruña, the Roman bridge with the lion in Ourense, etc.—, but the marks of Santiago changed successively each century: Saint James as a pilgrim (sixteenth century), a shell (seventeenth century), the tomb of Saint James (eighteenth century), a chalice with the holy form (nineteenth century) and the word ‘Santiago’ (twentieth century). Finally, we should mention the chronological mark, which refers to the year the piece was made, which is very useful for historians.
Jet
Jet is not a precious material, so it did not require such exhaustive controls, although it was necessary to ensure its quality and authenticity. It was important to verify that the jet carvers from Compostela used actual jet, and not similar materials such as lignite. Contrary to popular belief, jet is not a stone but a mineral-like, similar to coal, of plant origin, produced during the Jurassic period. Asturian jet is considered to be one of the best in the world, which is why most of the material used in Compostela throughout history has come from this neighbouring region.
