On our website you might have come across some terms that are difficult to understand because they are almost exclusively used by sector professionals. Check out our glossary to become familiar with these terms.

If you have any curiosities or questions or if you believe that some definitions are incomplete or incorrect, please contact us.
Your suggestions and requests will always be taken into consideration.

Note: some of the terms might have more than one meaning, depending on the context in which they are used. We want to point out that the definitions you will find here are solely referred to the jewelry sector.


Material originated from the melting of a metal with one or more elements. This combination always generates a product with specific characteristics and properties that are different from the ones of the original materials.

It is different from the majority of gemological materials because it has plant origin. It is a fossilized resin originating from extinct coniferous trees that grew tens of millions of years ago and sometimes it still contains insects that date back to the Eocene and that remained trapped in it. Amber is considered the queen of “organic gems” and in ancient times it was called “The Gold of The North”; it is often well imitated with various artificial resins that are all grouped together under a general name: “plastics”.

Along with the emerald, it is the most important variety of the beryl mineral group. Its natural colour is light-blue, greenish blue. The most common imitations are topaz, tourmaline and synthetic materials such as artificial glass, synthetic quartz and synthetic spinel. It is quite common to find gemstone doublets made of garnet and artificial glass, especially in old-fashioned items.

It is the cut that best valorizes diamonds, so much that, if not specified, “brilliant cut” refers to diamonds, even if it is a type of cut that can be used on various gems.
Diamonds with a brilliant cut have 57 facets, 58 when the culet is also faceted, which means that the culet is not sharp.

  • For gemstones: unit of measurement that establishes their weight and that is equivalent to 0,2 grams.
  • For gold: obsolete unit of measurement that establishes the gold contained in a gold alloy. It is a fractional measure equivalent to 1/24. Therefore if an alloy is 18 ct it means that it contains 18/24 of gold in weight (equivalent to 750 thousandths) and 6/24 of other metals.

A hard substance formed in the sea from masses of shells of very small sea animals that live in vast colonies, in waters of limited depths, with temperatures between 10 and 29 degrees Celsius. Amongst the various types of coral, only the so-called “noble” coral is used in the jewelry sector. The most common colours are pink and red.

Organic gems, even though they are obtained thanks to human intervention. Humans have tried to culture pearls for three thousands years, but only starting from 1900 they have managed to obtain significant results. In this case, human intervention consists in inserting a nucleus of nacre inside the mollusc. It is a quite difficult procedure. The dimensions of the pearl in the making are strictly linked to the size of the inserted nucleus: the bigger the foreign body, the higher the mortality rate of the mollusc. Pearls that are cultured in the sea have a completely different structure than the one of natural pearls: natural pearls have a very small, practically non-existent nucleus, whereas these pearls have a small sphere of nacre with flat or slightly curved layers. Pearls that are cultured in freshwaters, on the other hand, usually lack a solid nucleus because they are formed with the implantation of a small fragment of epithelium in the mollusc, which then secretes the nacreous substance.

It is a mineral, therefore a natural material. Its chemical compound is C, which stands for pure carbon. It has a crystal lattice that is very compact, which makes it the hardest material that we know of.

It is a variety of the beryl mineral group with small traces of chromium and, less often, of vanadium too, which characterize emerald’s typical and intense green tonality. Emerald, together with ruby and sapphire, is a precious gemstone. Its most ancient imitations are green glass and the most common are synthetic emeralds.

Ring with gemstones around the entire circumference.

It is the gold quotation set twice a day by the London Stock Exchange which establishes a price that determines all sales and purchases regarding gold at the moment of fixing.

Identification document, regularly signed by analysts, issued by the analysis lab after the examination of the gemstone. In the certificate you will find: number of the document, identification of the material – natural or synthetic – characteristics. Among the characteristics you will find: dimensions, shape, mass, colour, physical properties like specific weight and optical characteristics, inclusions, potential treatments.

Composite gemstone that imitates a gem, sometimes so accurately that it is hardly recognizable. It is a unit made of two parts, usually united through gluing, but also through other techniques that require human intervention.
Usually the gemstone doublet is made of a piece of a precious gemstone and a piece of a synthetic or less valuable gemstone. It is a type of imitation that is falling into disuse.
When the crown and the pavilion are united by two distinct parts of a rubbed off colour, and in the midst of these two parts a layer of synthetic material is interposed in order to have the desired coloring, we are talking about a triplet.

In the jewelry sector, glass or synthetic glass (since natural glass is considered a gem) are terms used to describe gems that are produced artificially through the employment of a vitreous substance, which is not a crystalline substance, in order to imitate mineral gems; the terms vitreous paste is also used for this same meaning.

It is considered the most important among the noble metals, and it is a chemical element marked by the symbol Au. It is very ductile and malleable, it is resistant to chemicals and atmospheric agents and it has an intensive yellow colour in nature.

It has always been used as a parameter for every kind of valuable item, for the minting of coins and for precious items. Gold is listed per gram or ounce. Because of its extreme malleability, it is not manufactured by itself but it is combined with other metals that make it more resistant.

Depending on the quantity of gold, there are different types of alloys, in which gold is measured in thousandths. For example if we have a gold item that weighs 10,0 g with a gold concentration of 750 thousandths it means that there are 7,5 g of pure gold (999,9/1000) and 2,5 g of other metals. They are precisely these 2,5 g of other metals that determine the colour of the alloy. For example, with 2 g of silver and 0,5 g of copper, the final colour will be pale yellow. On the contrary, with 2 g of copper and 0,5 of silver, the final colour will be a red gold.

In order to obtain white gold, white metals will need to be added, like palladium, that, unlike nickel, is non-allergenic. The gold concentration, expressed in thousandths, must be present on every item with a weight above 1 g, next to the manufacturer’s brand that, in so doing, takes responsibility for the gold concentration declared on the item.

On the Italian market you can almost exclusively find items with a gold concentration of 750 thousandths, which is also obsoletely called 18 ct gold.

Here you can find a chart with the most common alloys and the respective worth in carats:



















From the greek grammax, which means small weight. It is a unit of measurement for mass in the MKS system of units (meter-kilogram-second) and it is the equivalent of a thousandth of 1kg. In the jewelry sector the gram is used as a unit of weight for valuable metals like gold. Its symbol is g.

Synthetic, assembled material or treated material that is very similar to the gem that it imitates, but differs in chemical and/or physical properties and crystal structure. It should be noted though that, generally speaking, imitation can also refer to the so-called Similar Gems, that are natural and non-treated materials used as imitations of other gems because of their similarity with them. The gemstones that are usually imitated are valuable gemstones, such as ruby, sapphire, emerald, diamonds.

An inclusion can be a fracture, a solid, liquid or gaseous material of a different nature from the one of the main gemstone, or it can also be a structural characteristic present inside the gemstone.

It can be natural or derived from a synthesis or a treatment of the gemstone. In the vast majority of cases an inclusion compromises the beauty of the stone, but in some rare cases it can also positively characterize the stone with optical effects that make the gemstone unique.

Organic gems. They are concretions originated by some types of molluscs, bivalve or gastropod, around a foreign body that enters inside their mantle. Only a few species of molluscs create good results in the pearl formation, in fact, perfectly rounded pearls are very rare and precious. For the most part, pearls have an irregular shape. Their colour can vary: creamy white, rosy-white, brownish-white, silvery white. There still isn’t a unanimous opinion on the causes of this colour variety: some state that the colour depends on the pigment inside the nacre of the shell, while others believe that it depends on different joint causes, like for example the level of salinity of the water, the type of plankton present in the water, etc. The pearls sold in jewelries are for the most part cultured pearls, because natural pearls are extremely rare.

It is a unit of measurement that is only used for valuable metals, like gold. It is the equivalent of 31,103 grams and it is a unit of measurement typically used in english-speaking countries.

It is a gemstone that is made or derived from living organisms. The most famous and appreciated are amber, coral and pearls

An organic substance is a natural product of animal or plant origin. Even when human intervention happens, like in the case of cultured pearls, we can still talk about organic substance, as long as the formation of the substance happens also thanks to the component of plant or animal origin.

A French term that indicates a street paved with small cubic stones. This term is used in the jewelry sector to describe a type of setting obtained by mounting gemstones very closely to one another in order to have a layer of gemstones that radiate light altogether. This technique is very similar to the one used by pavers on the streets, which explains why this term is used.

Noble, silvery white, malleable metal that is particularly resistant to chemical agents. In the jewelry sector it is often used in alloys. Its chemical symbol is Pt.

It consists in covering a metal, through electrolysis, with a layer of rhodium in order to make it whiter. Thanks to rhodium plating a yellow gold item can become white.

Along with sapphire, it is the most precious variety of the corundum mineral species. Ruby is characterized by an intense red colour, mainly due to the presence of chromium in the mineral crystal structure. However this colour can have different shades that go from bright red to purple red or brownish red. Ruby, together with sapphire and emerald, is a precious gemstone and its most frequent imitations are synthetic rubies.

It is the blue variety of the corundum mineral species. Its colour derives from iron and titanium inclusions and it has a vast range of shades that go from blue and purple blue to greenish blue. Sapphire, together with ruby and emerald, is a precious gemstone and its most frequent imitations are synthetic sapphires.

It is a noble, shiny greyish-white metal, malleable, very ductile and valuable. It has been used since ancient times in the manufacture of luxury items and coins. Its chemical symbol is Ag.

They are every gemstone that has been artificially produced (regardless of the method) and that has composition, crystal structure and some physical properties of a specific mineral. Since the gemstone is produced by humans, it has no commercial value. The expertise of a gemologist is necessary in order to recognize a natural gemstone from a synthetic one; sometimes the elements that enable the identification are difficult to interpret, therefore lab examinations become necessary in order to obtain the final result.

There are various methods of synthesis and due to the improvement of identification techniques through gemological analysis, new methods appear all the time.

Ring with three brilliant cut stones.

Term normally and often wrongly used to describe the synthetic product “cubic zirconia”, which is the crystalline cubic shape of the zirconium dioxide, with exclusively synthetic origin and which is created to (successfully) imitate  diamonds. They are almost always colourless, even if they can be produced in a variety of different colours and usually they present a brilliant cut.
The “actual” zircon is a mineral, a natural substance made of zirconium silicate and its range of colours includes: colourless, blue, pink, orange, yellow, brown, brownish-green, olive drab. It is not used in the jewelry sector.


An analog watch shows the time using numbers around the edge and hands that point to the numbers. They are the opposite of digital watches.

It is a type of surface treatment of glass in order to obtain a clearer reading of time thanks to the scattering of reflected light.

An automatic watch, also known as self-winding watch or simply automatic, is a mechanical watch in which the natural motion of the wearer provides energy to wind the mainspring, making manual winding unnecessary.

Revolving component placed in the central part of the case (called “carrure”). The bezel allows you to: keep track of a second time zone, measure time etc. on the basis of one or more scales located on the surface. In divers’ watches this scale is sexagesimal and the bezel is unidirectional because it makes it easier to keep track of the dive time.

It is a complication that displays date, day of the week and month of the year and that requires a manual adjustment, at the end of the month, only for those months with less than 31 days.

French term to indicate the central part of the watch case. Usually the lugs of the strap are fixed to the carrure.

The watch case is the supporting structure of the watch that characterizes its shape and at the same time protects it from external stresses. The most common shapes are: rectangular, square, oval, round and tonneau.

The rear part of the case, blocked with screws or directly screwed on the case, or also pressure sealed.

It gives further time measurements, calculated by the mechanism and its complications.

Little knob placed on the carrure which allows charging and regulation of spheres and other counters, if present.

It is a device that allows you to measure time intervals. It is managed thanks to the buttons on the watch case.

In the watchmaking industry this term identifies a model designed to guarantee maximum precision. This term can be used only after the watch has passed a number of tests with an error included between -3 and +6 seconds per day, in different temperature conditions and for a period of time of at least 15 days. If the watch passes these tests, it will have the “chronometer” certificate issued by COSC (Contrôle Officiel Suisse de Chronomètres). In everyday language this term is often mistakenly used to indicate the chronograph.

Part of the strap that unites its two halves and works as a buckle. It is usually made of the same material used for the case.

A plate, face or other surface of a watch that is marked to show units of time. It is usually made of metal, protected by a glass and it can be decorated in various ways according to the design of the watch.

A watch that displays time in the form of numbers, rather than by a dial and hands. The term derives from the english word “digit”.

It is the component that protects the dial. Depending on the watch, the glass can be tempered glass or sapphire, but also plexiglass.

Used to indicate hours, minutes, seconds and other things on graduated scales. It is usually made of metal and it can have various shapes according to the design of the watch.

All the symbols that indicate hours, minutes or other time measurements.

They indicate the different shapes of the Moon that are generated from its different orientation in relation to the Sun. A lunation lasts 29 days, 12 hours, 44 minutes and 2,8 seconds, rounded off to 29 days and 12 hours. Some watches have a complication that allows you to see the lunar phases.

The term movement describes the entirety of a watch’s engines and it can be: quartz movement and mechanical movement. The latter has a further distinction between self-winding mechanical movement and manual-winding mechanical movement.

It is a complication that displays date, day of the week and month of the year but requires less adjustment than a complete calendar. This complication knows the number of days in each month and also the lunar phases.

It is a complication which is designed to show the amount of remaining stored energy.

A waterproof watch is a watch in which the internal parts cannot be reached by water. The degree of impermeability is expressed in standard atmosphere (atm) or according to the depth of the dive, which is expressed in meters. 1 atm = 10 mt.