A gemstone is a piece of mineral crystal which, when cut or polished, is used to make jewelry or other adornments. Certain rocks and occasionally organic materials that are not minerals may also be used for jewelry and are therefore often considered to be gemstones as well. Most gemstones are hard, but some softer minerals such as brazilianite may be used in jewelry because of their color or luster or other physical properties that have aesthetic value. However, generally speaking, soft minerals are not typically used as gemstones by virtue of their brittleness and lack of durability.
Topaz is a silicate mineral made of aluminum and fluorine with the chemical formula Al2SiO4(F, OH)2. It is used as a gemstone in jewelry and other adornments. Common topaz in its natural state is colorless, though trace element impurities can make it pale blue or golden brown to yellow-orange. Topaz is often treated with heat or radiation to make it a deep blue, reddish-orange, pale green, pink, or purple.
Lapidary is the practice of shaping stone, minerals, or gemstones into decorative items such as cabochons, engraved gems, and faceted designs. A person who practices lapidary techniques of cutting, grinding, and polishing is known as a lapidary or lapidarist. Hardstone carving requires specialized carving techniques.
Diamond cutting is the practice of shaping a diamond from a rough stone into a faceted gem. Cutting diamonds requires specialized knowledge, tools, equipment, and techniques because of its extreme difficulty.
A tiara is a jeweled head ornament. Its origins date back to ancient Greco-Roman world. In the late 18th century, the tiara came into fashion in Europe as a prestigious piece of jewelry to be worn by women at formal occasions. The basic shape of the modern tiara is a semi-circle, usually made of silver, gold or platinum and richly decorated with precious stones, pearls or cameos.
Facets are flat faces on geometric shapes. The organization of naturally occurring facets was key to early developments in crystallography, since they reflect the underlying symmetry of the crystal structure. Gemstones commonly have facets cut into them in order to improve their appearance by allowing them to reflect light.
A diamond cut is a style or design guide used when shaping a diamond for polishing such as the brilliant cut. Cut refers to shape, and also the symmetry, proportioning and polish of a diamond. The cut of a diamond greatly affects a diamond's brilliance—a poorly-cut diamond is less luminous.
A diamond simulant, diamond imitation or imitation diamond is an object or material with gemological characteristics similar to those of a diamond. Simulants are distinct from synthetic diamonds, which are actual diamonds exhibiting the same material properties as natural diamonds. Enhanced diamonds are also excluded from this definition. A diamond simulant may be artificial, natural, or in some cases a combination thereof. While their material properties depart markedly from those of diamond, simulants have certain desired characteristics—such as dispersion and hardness—which lend themselves to imitation. Trained gemologists with appropriate equipment are able to distinguish natural and synthetic diamonds from all diamond simulants, primarily by visual inspection.
A gemstone desired to be used in jewelry is cut depending on the size and shape of the rough stone, as well as the desired piece of jewelry to be made. As a general rule, a cut gemstone will reduce the mass by about 50%.
Lodewyk van Bercken was a mid- to late-15th century Flemish jeweller and diamond cutter, renowned in the industry for inventing the scaif. The device revolutionized the diamond cutting industry and contributed to increased popularity of diamonds.
Stonesetting is the art of securely setting or attaching gemstones into jewelry.
Prong setting or prong mount refers to the use of metal projections or tines, called "prongs", to secure a gemstone to a piece of jewelry. A prong setting is one component of what is known to jewelers as a head, a claw-shaped type of binding that is welded or soldered to a jewelry item to mount a gemstone to the jewelry item. A common setting for diamond engagement rings, the prong setting allows light to strike a gemstone from more angles, increasing its brilliance.
A faceting machine is broadly defined as any device that allows the user to place and polish facets onto a mineral specimen. Machines can range in sophistication from primitive jamb-peg machines to highly refined, and highly expensive, commercially available machines. A major division among machines is found between those that facet diamonds and those that do not. Specialized equipment is required for diamond faceting, and faceting as an occupation rarely bridges the gap between diamond and non-diamond workmanship. A second division can be made between industrial faceting and custom/hobby faceting. The vast majority of jewelry-store gemstones are faceted either abroad in factories or entirely by machines. Custom jewelry is still commonly made of custom metalwork and mass-produced gemstones, but unusual cuts or particularly valuable gemstone material will likely be faceted on a personal faceting machine.
A bezel is a wider and usually thicker section of the hoop of a ring, which may contain a gem or a flat surface. Rings are normally worn to display bezels on the upper or outer side of the finger. In gem-cutting the term bezel is used for those sloping facets of a cut stone that surround the flat table face, which is the large, horizontal facet on the top.
Diamond is a gemstone formed by cutting a raw diamond. Diamonds are one of the best-known and most sought-after gems, and they have been used as decorative items since ancient times.
The Napoleon Diamond Necklace is a diamond necklace commissioned by Napoleon I of France c. 1811–1812 from the Parisian jeweler Marie-Étienne Nitot. It is now in the Smithsonian National Museum of Natural History in Washington, D.C.
A pendeloque cut is a pear-shaped modification of the round brilliant cut used for diamonds and other gemstones. The pendeloque cut is sometimes erroneously called briolette cut, another drop-shaped cutting design. While the briolette is a symmetrical drop shape, the pendeloque cut is flatter and has two different sides: one with a large table facet and one with a point or ridge. The top of a briolette is attached to the piece of jewelry, usually by a hole drilled in the stone, and a pendeloque cut stone needs to be mounted in a prong setting. The pendeloque is one of the drop cuts for gemstones.
A rivière is a necklace consisting of one or more strings of linked gemstones. Usually only one kind of gemstone is used in a rivière, with all stones of the same colour and cut. The stones are either all the same size, or gradually increase in size towards the middle of the necklace. Rivières have been worn since the 18th century and are still a popular type of necklace.
The Marie Louise Diadem is a diamond and turquoise diadem on permanent display at the National Museum of Natural History in Washington D.C.. It is named for Marie Louise of Austria, the wife of Emperor Napoleon of France.
A pendeloque, from French pendeloque, is a hanging often drop- or pear-shaped object or pendant used as an ornamentation, such as drop-shaped pendant earrings, and specific pear- and drop-shaped parts of chandeliers. The term is also used in describing the specific pendeloque cut for gemstone cutting.
