Hardstone is a non-scientific term, mostly encountered in the decorative arts or archaeology, that has a similar meaning to semi-precious stones, or gemstones.[1] Very hard building stones, such as granite, are not included in the term in this sense, but only stones which are fairly hard and regarded as attractive– ones which could be used in jewellery. Hardstone carving is the three-dimensional carving for artistic purposes of semi-precious stones such as jade, agate, onyx, rock crystal, sard or carnelian, and a general term for an object made in this way. Two-dimensional inlay techniques for floors, furniture and walls include pietre dure, opus sectile (Ancient Roman), and medieval Cosmatesque work– these typically inlay hardstone pieces into a background of marble or some other building stone.
The definition of "hardstone" is not very rigid, but excludes "soft" stones such as soapstone (steatite) and minerals such as alabaster, both widely used for carving. Hard organic minerals such as amber and jet are included, as well as the mineraloidobsidian. Geologically speaking, most of the gemstones carved in the West are varieties of quartz, including chalcedony, agate, amethyst, sard, onyx, carnelion, heliotrope, jasper and quartz in its uncoloured form, known as rock crystal. On the Mohs scale of mineral hardness, quartz rates no higher than a 7, less for types with impurities. Stones typically used for buildings and large sculpture are not often used for small objects such as vessels, although this does occur.
The term is derived from a literal translation of the Italian plural pietre dure, 'hard stones', which in Italian covers all hardstone carving. The semi-anglicized singular pietra dura is used in English for multi-coloured stone inlay work, in fact using marbles as much as semi-precious stones, which was a Florentine speciality from the Renaissance onwards. Pietre dure is sometimes used for Italian or European vessels and small sculptures of the same period.[2]
Agate is a common rock formation, consisting of chalcedony and quartz as its primary components, consisting of a wide variety of colors. Agates are primarily formed within volcanic and metamorphic rocks. The ornamental use of agate dates back to Ancient Greece in assorted jewelry and in the seal stones of Greek warriors.
A gemstone is a piece of mineral crystal which, in cut and polished form, is used to make jewelry or other adornments. However, certain rocks and occasionally organic materials that are not minerals are also used for jewelry and are therefore often considered to be gemstones as well. Most gemstones are hard, but some soft minerals are used in jewelry because of their luster or other physical properties that have aesthetic value. Rarity is another characteristic that lends value to a gemstone.
Quartz is a hard, crystalline mineral composed of silicon and oxygen atoms. The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO2. Quartz is the second most abundant mineral in Earth's continental crust, behind feldspar.
Chalcedony is a cryptocrystalline form of silica, composed of very fine intergrowths of quartz and moganite. These are both silica minerals, but they differ in that quartz has a trigonal crystal structure, while moganite is monoclinic. Chalcedony's standard chemical structure (based on the chemical structure of quartz) is SiO2 (silicon dioxide).
Carnelian is a brownish-red mineral commonly used as a semi-precious gemstone. Similar to carnelian is sard, which is generally harder and darker. Both carnelian and sard are varieties of the silica mineral chalcedony colored by impurities of iron oxide. The color can vary greatly, ranging from pale orange to an intense almost-black coloration. It is most commonly found in Indonesia, Brazil, India, Russia (Siberia), and Germany.
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 is known as a lapidarist. A lapidarist uses the lapidary techniques of cutting, grinding, and polishing. Hardstone carving requires specialized carving techniques.
Cameo is a method of carving an object such as an engraved gem, item of jewellery or vessel. It nearly always features a raised (positive) relief image; contrast with intaglio, which has a negative image. Originally, and still in discussing historical work, cameo only referred to works where the relief image was of a contrasting colour to the background; this was achieved by carefully carving a piece of material with a flat plane where two contrasting colours met, removing all the first colour except for the image to leave a contrasting background.
Onyx primarily refers to the parallel banded variety of the silicate mineral chalcedony. Agate and onyx are both varieties of layered chalcedony that differ only in the form of the bands: agate has curved bands and onyx has parallel bands. The colors of its bands range from black to almost every color. Commonly, specimens of onyx contain bands of black and/or white. Onyx, as a descriptive term, has also been applied to parallel banded varieties of alabaster, marble, obsidian and opal, and misleadingly to materials with contorted banding, such as "Cave Onyx" and "Mexican Onyx".
Objet d'art literally means "art object" in French, but in practice, the term has long been reserved in English to describe works of art that are not paintings, large or medium-sized sculptures, prints, or drawings. It therefore covers a wide range of works, usually small and three-dimensional, of high quality and finish in areas of the decorative arts, such as metalwork items, with or without enamel, small carvings, statuettes and plaquettes in any material, including engraved gems, hardstone carvings, ivory carvings and similar items, non-utilitarian porcelain and glass, and a vast range of objects that would also be classed as antiques, such as small clocks, watches, gold boxes, and sometimes textiles, especially tapestries. Books with fine bookbindings might be included.
The priestly breastplate was a sacred breastplate worn by the High Priest of the Israelites, according to the Book of Exodus. In the biblical account, the breastplate is sometimes termed the breastplate of judgment, because the Urim and Thummim were placed within it. These stones were, at times, used to determine God's will in a particular situation. Using these stones did not always determine God's will
Pietra dura or pietre dure[ˈpjɛːtre ˈduːre], called parchin kari or parchinkari in the Indian Subcontinent, is a term for the inlay technique of using cut and fitted, highly polished colored stones to create images. It is considered a decorative art. The stonework, after the work is assembled loosely, is glued stone-by-stone to a substrate after having previously been "sliced and cut in different shape sections; and then assembled together so precisely that the contact between each section was practically invisible". Stability was achieved by grooving the undersides of the stones so that they interlocked, rather like a jigsaw puzzle, with everything held tautly in place by an encircling 'frame'. Many different colored stones, particularly marbles, were used, along with semiprecious, and even precious stones. It first appeared in Rome in the 16th century, reaching its full maturity in Florence. Pietra dura items are generally crafted on green, white or black marble base stones. Typically, the resulting panel is completely flat, but some examples where the image is in low relief were made, taking the work more into the area of hardstone carving.
Intarsia is a form of wood inlaying that is similar to marquetry. The start of the practice dates from before the seventh century AD.
Aqeeq, akik or aqiq means quartz in Arabic, and agate in Turkish, however in the context of rings usually refers to a ring set with a chalcedony stone. Well-known types of chalcedony are carnelian, agate, and onyx. It is considered a semi-precious gem stone, and rings set with golden-orange variety of carnelian or sard have special significance in the Islamic religion.
A Stone sculpture is an object made of stone which has been shaped, usually by carving, or assembled to form a visually interesting three-dimensional shape. Stone is more durable than most alternative materials, making it especially important in architectural sculpture on the outside of buildings.
Inlay covers a range of techniques in sculpture and the decorative arts for inserting pieces of contrasting, often coloured materials into depressions in a base object to form ornament or pictures that normally are flush with the matrix. A great range of materials have been used both for the base or matrix and for the inlays inserted into it. Inlay is commonly used in the production of decorative furniture, where pieces of coloured wood, precious metals or even diamonds are inserted into the surface of the carcass using various matrices including clearcoats and varnishes. Lutherie inlays are frequently used as decoration and marking on musical instruments, particularly the smaller strings.
The Opificio delle pietre dure, literally meaning Workshop of semi-precious stones, is a public institute of the Italian Ministry for Cultural Heritage based in Florence. It is a global leader in the field of art restoration and provides teaching as one of two Italian state conservation schools. The institute maintains also a specialist library and archive of conservation and a museum displaying historic examples of pietre dure inlaid semi-precious stones artefacts. A scientific laboratory conducts research and diagnostics and provides a preventive conservation service.
A range of gemstones are mentioned in the Bible, particularly in the Old Testament and the Book of Revelation. Much has been written about the precise identification of these stones, although largely speculative.
Hardstone carving is a general term in art history and archaeology for the artistic carving of predominantly semi-precious stones, such as jade, rock crystal, agate, onyx, jasper, serpentinite, or carnelian, and for an object made in this way. Normally the objects are small, and the category overlaps with both jewellery and sculpture. Hardstone carving is sometimes referred to by the Italian term pietre dure; however, pietra dura is the common term used for stone inlay work, which causes some confusion.
Pio Siotto was an Italian artist active as a cameo engraver.
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