The cable chain and the link chain are two of the most classic forms of chain; theircharacteristic are oval connections, which are arranged alternately in horizontal and vertical orientation. The cable chain is one of the strongest types of chains. It serves as the basic form for many variations: for example, the outer surfaces of individual connections can be flattened (flat cable chain) or slightly rounded (rounded cable chain).

The cabochon cut the numbers between the so-called "smooth cuts" in which the smooth surface of the stone is not divided into facets. Also known as the "mugel cut", the cabochon is the oldest known cut for gems. Connoisseurs distinguish between ball-shaped cabochons, which resemble a hemisphere prone in the side view, and conical cabochons, which climb steeply to a rounded point in the side view.

The word "carat" is also sometimes written with a "K", but is always abbreviated "ct". Carat has been used since classical antiquity as a unit of weight for jewelry stones and pearls. Carat, should not be confused with "carat" as a degree of purity for gold alloys. Both words derive either from the Greek word "keration" (the fruit of the carob tree) or from the kuara seed of the African coral tree. One metric carat weighs 0.2 grams. Jewelry enthusiasts are particularly interested in the weight, i.e. the number of carats, of diamonds. A legendary type of diamond is the "one carat": that is, a diamond of 6.5 mm in diameter and an exact weight of 0.2 grams. A "half carat" measures 5.2 mm in diameter. A "two-carat" has a diameter of 8.2 mm.

The carré cut, also known as square cut, is a quadratic form for transparent gemstones. Its quadratic table is usually surrounded by a terraced edge consisting of two rows of facets.

Many years ago, Chinese pearl farmers began growing coreless freshwater pearls in oysters that they grew in tributaries and canals of the Yangtse river system. Chinese freshwater pearls have an attractive, almost spherical shape. The largest can have a diameter of 10 mm. The color spectrum ranges from white, pink and green to intense shades of red and lilac. In the process of cultivation, some living tissue that forms mother-of-pearl is grafted into the body of the oyster so that these pearls have no core and consist entirely of nacre.

A "choker" is a necklace that clings close to the neck.. A short, tight-fitting chain made of meshes or a necklace that hugs the neck made of one or more strings of pearls can be described as a "choker". All pearls in a pearl choker are identical in size.

CIBJO is the international professional confederation of the jewellery industry. Founded in 1926, the organization has been called "Confédération Internationale de la Bijouterie, Joaillerie, Orfèvrerie, Perles et Pierres" since 1961. All major industrial nations are members. Among the most important tasks of CIBJO is to designate exact names and descriptions for precious stones and pearls. These official designations are listed in the so-called "Blue Book".

Citrine is a member of the quartz group. The synonyms are "gold topaz", "Madeira topaz" or "Spanish topaz", although these citrines only superficially resemble true topaz because they share a color similar to that gemstone. The name "citrine" comes from the lemon yellow color, although the most avidly coveted citrines are clear, from bright yellow to red-red. Citrine is a hard, non-fissile, and relatively durable stone. The main sources are Brazil, Madagascar and the United States.

A "collier de chien" is a tight, wide or multi- strand necklace. It was the most popular piece of jewelry during the 1920s and played an important role in the fashions of the late fifteenth and mid-eighteenth centuries. Nowadays the form collier de chien is interpreted in many different ways. Necklaces of this type are also available with pearls, diamonds or colored stones. The name comes from the French language and literally means “dog collar”.

The technical term "color" is one of the four quality criteria (the "4 Cs") according to which the value of a diamond is determined. Stones are judged in comparison with color scales. Most of these scales have 12 quality grades. The highest grade is "very fine white", which is used to describe diamonds that are absolutely colorless. Diamonds of this quality are identified by the letters "D" and "E" or by the term "river". "Fine white" diamonds are identified by the letters "F" and "G" or by the phrase "Top Wesselton". White stones are identified by the letter "H" or the word "Wesselton". Most diamonds are delicately dyed in color, often with a slightly yellowish cast.

The phrase "colored stone" is used for all precious stones except diamonds and agates. On the other hand, colorless gemstones are sometimes included in the category of "colored stones". The term "colored gemstone" is also often used to emphasize their preciousness.

The connected necklace is a classic and very feminine chain. It consists of round, bulky elements that are alternately connected horizontally and vertically to each other. The appearance of this type of chain varies depending on the thickness and size of its individual connections.

Corals grow in the ocean at depths of 300 meters or less. Soft polyps very slowly build branched structures by excreting a calcesque substance from their disc-like feet. The coral is therefore the scaffolding of the polyps, which live in small indentations in the branches. Coral quality jewelry, which grows mainly in the Mediterranean Sea and the Pacific Ocean, occurs in a wide variety of red and pink hues. Especially desirable are the deep red variety, which experts call coral "dull blood" or "brown", and a dusty pink variety known as "angel skin".

Corundum is essentially colorless. If there are traces of other elements (mainly iron and chromium), the corundum can display each color of the rainbow. Colorless corundum is a precious gemstone; after centuries of confusion in nomenclature, the international convention has now agreed to use the word "ruby" to describe the red corundum and use the word "sapphire" to name corundum stones in all other colors. The word "corundum" comes from a language spoken in the Indian subcontinent, where the language a similar word meant "hard stone". This etymology is really appropriate because with a hardness of "9" on the scale of the Mohs, the corundum is the second hardest stone in the world, surpassed in hardness only by diamond. Corundums are found on every continent.

The Cullinan is the "Star of Africa". The largest rough diamond ever found was named after Sir Thomas Cullinan, the director of a South African mine where this diamond, which weighed 3,106 carats, was discovered in 1905. Nine important, large diamonds and 96 smaller stones were cut from this rough diamond. Large diamonds have consecutive numbers. The largest of the nine, called Cullinan I, weighs 530 carats and is the largest cut diamond in the world, a distinction that earned it the shrewd "Star of Africa". It adorns the scepter of the Queen of England and is kept in the Tower of London.

The cultured pearl is the English equivalent of the term that is most frequently used in Austria and Switzerland to describe cultured pearls. Pearls are typically grown by inserting a core (usually a turned spherula made of natural mussel shell) into a bivalve along with a piece of living tissue that produces mother-of-pearl. The bivalve is returned to water, where it is continuously monitored and regularly purified. The implanted tissue continues to produce mother of pearl, with which it covers the core. The bivalve takes at least 18 months to produce a cultured pearl.

The cut is the treatment given to the surface of a coloured stone or diamond. A good cut can reveal the gem's intrinsic beauty, colour and sparkle. Lapidary art was probably first practised in India. Before and in the 15th century, the treatment given to gemstones usually consisted exclusively of polishing their surfaces with natural crystal or cleavage. During the 15th century, faceted cuts became widely known. Coloured stones are polished by abrasion with polishing discs made of lead, bronze, copper or tin. Diamonds can only be cut from other diamonds. The toughness of a diamond varies depending on the particularities of its crystal planes and its different axes. Many of the steps involved in polishing and cutting coloured stones and diamonds cannot be carried out by machines and must be done manually.

The cut heart permeates diamonds and colored stones with a touch of romance. As the name implies, a heart-cut stone has the shape of a heart. To achieve this, a triangular or heart-shaped table is surrounded by numerous facets that enhance the twinkle and glow of the gem.