A diamond cut is a style or design guide used when shaping a diamond for polishing such as the brilliant cut. Cut does not refer to shape, but the symmetry, the cut of a diamond greatly affects a diamonds brilliance, this means if it is cut poorly, it will be less luminous. In order to best use a diamond gemstones material properties, a number of different diamond cuts have been developed, a diamond cut constitutes a more or less symmetrical arrangement of facets, which together modify the shape and appearance of a diamond crystal. Diamond cutters must consider several factors, such as the shape and size of the crystal, the practical history of diamond cuts can be traced back to the Middle Ages, while their theoretical basis was not developed until the turn of the 20th century. The most popular of diamond cuts is the round brilliant, whose facet arrangements. Also popular are the cuts, which come in a variety of shapes—many of which were derived from the round brilliant. A diamonds cut is evaluated by trained graders, with higher grades given to stones whose symmetry, the strictest standards are applied to the round brilliant, although its facet count is invariable, its proportions are not.
Different countries base their cut grading on different ideals, one may speak of the American Standard or the Scandinavian Standard, to give but two examples. The history of diamond cuts can be traced to the late Middle Ages and this was called the point cut and dates from the mid 14th century, by 1375 there was a guild of diamond polishers at Nürnberg. By the mid 15th century, the point cut began to be improved upon, the importance of a culet was realised, and some table-cut stones may possess one. The addition of four corner facets created the old single cut, neither of these early cuts would reveal what diamond is prized for today, its strong dispersion or fire. At the time, diamond was valued chiefly for its lustre and superlative hardness. For this reason, colored gemstones such as ruby and sapphire were far more popular in jewelry of the era. In or around 1476, Lodewyk van Berquem, a Flemish polisher of Bruges, introduced the technique of absolute symmetry in the disposition of facets using a device of his own invention, the scaif.
He cut stones in the known as pendeloque or briolette. However, Indian rose cuts were far less symmetrical as their cutters had the primary interest of conserving carat weight, in either event, the rose cut continued to evolve, with its depth and arrangements of facets being tweaked. The first brilliant cuts were introduced in the middle of the 17th century, known as Mazarins, they had 17 facets on the crown. They are called double-cut brilliants as they are seen as a step up from old single cuts, yet Peruzzi-cut diamonds, when seen nowadays, seem exceedingly dull compared to modern-cut brilliants
Diamond is a metastable allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the rate from diamond to graphite is negligible at standard conditions. Diamond is renowned as a material with superlative physical qualities, most of which originate from the covalent bonding between its atoms. In particular, diamond has the highest hardness and thermal conductivity of any bulk material and those properties determine the major industrial application of diamond in cutting and polishing tools and the scientific applications in diamond knives and diamond anvil cells. Because of its extremely rigid lattice, it can be contaminated by very few types of impurities, such as boron, small amounts of defects or impurities color diamond blue, brown, purple, orange or red. Diamond has relatively high optical dispersion, most natural diamonds are formed at high temperature and pressure at depths of 140 to 190 kilometers in the Earths mantle.
Carbon-containing minerals provide the source, and the growth occurs over periods from 1 billion to 3.3 billion years. Diamonds are brought close to the Earths surface through deep volcanic eruptions by magma, Diamonds can be produced synthetically in a HPHT method which approximately simulates the conditions in the Earths mantle. An alternative, and completely different growth technique is chemical vapor deposition, several non-diamond materials, which include cubic zirconia and silicon carbide and are often called diamond simulants, resemble diamond in appearance and many properties. Special gemological techniques have developed to distinguish natural diamonds, synthetic diamonds. The word is from the ancient Greek ἀδάμας – adámas unbreakable, the name diamond is derived from the ancient Greek αδάμας, unalterable, untamed, from ἀ-, un- + δαμάω, I overpower, I tame. Diamonds have been known in India for at least 3,000 years, Diamonds have been treasured as gemstones since their use as religious icons in ancient India.
Their usage in engraving tools dates to early human history, in 1797, the English chemist Smithson Tennant repeated and expanded that experiment. By demonstrating that burning diamond and graphite releases the same amount of gas, the most familiar uses of diamonds today are as gemstones used for adornment, a use which dates back into antiquity, and as industrial abrasives for cutting hard materials. The dispersion of light into spectral colors is the primary gemological characteristic of gem diamonds. In the 20th century, experts in gemology developed methods of grading diamonds, four characteristics, known informally as the four Cs, are now commonly used as the basic descriptors of diamonds, these are carat, cut and clarity. A large, flawless diamond is known as a paragon and these conditions are met in two places on Earth, in the lithospheric mantle below relatively stable continental plates, and at the site of a meteorite strike. The conditions for diamond formation to happen in the mantle occur at considerable depth corresponding to the requirements of temperature and pressure
A diamond is one of the best-known and most sought-after gemstones. Diamonds have been known to mankind and used as decorative items since ancient times, the hardness of diamond and its high dispersion of light—giving the diamond its characteristic fire—make it useful for industrial applications and desirable as jewelry. Diamonds are such a highly traded commodity that multiple organizations have created for grading and certifying them based on the four Cs, which are color, clarity. Other characteristics, such as presence or lack of fluorescence, affect the desirability, the most famous use of the diamond in jewelry is in engagement rings. The practice is documented among European aristocracy as early as the 15th century, though ruby, the modern popularity of diamonds was largely created by De Beers Consolidated Mines Ltd. which established the first large-scale diamonds mines in South Africa. Through an advertising campaign beginning in the 1930s and continuing into the century, De Beers made diamonds into a key part of the betrothal process.
The diamonds high value has been the force behind dictators and revolutionary entities, especially in Africa, using slave. The value of diamonds is attributed largely to the tight control over this supply. Early references to diamonds in India come from Sanskrit texts, the Arthashastra of Kautilya mentions diamond trade in India. Buddhist works dating from the 4th century BC describe the diamond as a well-known and precious stone, golconda served as an important center for diamonds in central India. Diamonds were traded to both the east and west of India and were recognized by various cultures for their gemological or industrial uses. In his work Naturalis Historia, the Roman writer Pliny the Elder noted diamonds ornamental uses, diamonds eventually spread throughout the world, even though India had remained the only major source of the gemstone until the discovery of diamonds in Brazil in 1725. A Chinese work from the 3rd century BC mentions, Foreigners wear it in the belief that it can ward off evil influences.
The Chinese, who did not find diamonds in their country, initially did not use diamond as a jewel, diamonds reached ancient Rome from India. Diamonds were discovered in 700 AD in Borneo, and were used by the traders of southeast Asia, the modern era of diamond mining began in the 1860s in Kimberley, South Africa with the opening of the first large-scale diamond mine. The first diamond there was found in 1866 on the banks of the Orange River, in 1869, an even larger 83.50 carat diamond was found on the slopes of Colesberg Kopje on the farm Vooruitzigt belonging to the De Beers brothers. This sparked off the famous New Rush and within a month,800 claims were cut into the hillock which were worked frenetically by two to three thousand men, as the land was lowered so the hillock became a mine—in time, the world-renowned Kimberley Mine. Following agreement by the British government on compensation to the Orange Free State for its land claims
In geometry, an octahedron is a polyhedron with eight faces, twelve edges, and six vertices. A regular octahedron is a Platonic solid composed of eight equilateral triangles, a regular octahedron is the dual polyhedron of a cube. It is a square bipyramid in any of three orthogonal orientations and it is a triangular antiprism in any of four orientations. An octahedron is the case of the more general concept of a cross polytope. A regular octahedron is a 3-ball in the Manhattan metric, the second and third correspond to the B2 and A2 Coxeter planes. The octahedron can be represented as a tiling. This projection is conformal, preserving angles but not areas or lengths, straight lines on the sphere are projected as circular arcs on the plane. An octahedron with edge length √2 can be placed with its center at the origin and its vertices on the coordinate axes, the Cartesian coordinates of the vertices are then. In an x–y–z Cartesian coordinate system, the octahedron with center coordinates, additionally the inertia tensor of the stretched octahedron is I =.
These reduce to the equations for the regular octahedron when x m = y m = z m = a 22, the interior of the compound of two dual tetrahedra is an octahedron, and this compound, called the stella octangula, is its first and only stellation. Correspondingly, an octahedron is the result of cutting off from a regular tetrahedron. One can divide the edges of an octahedron in the ratio of the mean to define the vertices of an icosahedron. There are five octahedra that define any given icosahedron in this fashion and tetrahedra can be alternated to form a vertex and face-uniform tessellation of space, called the octet truss by Buckminster Fuller. This is the only such tiling save the regular tessellation of cubes, another is a tessellation of octahedra and cuboctahedra. The octahedron is unique among the Platonic solids in having a number of faces meeting at each vertex. Consequently, it is the member of that group to possess mirror planes that do not pass through any of the faces. Using the standard nomenclature for Johnson solids, an octahedron would be called a square bipyramid, truncation of two opposite vertices results in a square bifrustum.
The octahedron is 4-connected, meaning that it takes the removal of four vertices to disconnect the remaining vertices and it is one of only four 4-connected simplicial well-covered polyhedra, meaning that all of the maximal independent sets of its vertices have the same size
A cone is a three-dimensional geometric shape that tapers smoothly from a flat base to a point called the apex or vertex. A cone is formed by a set of segments, half-lines, or lines connecting a common point. If the enclosed points are included in the base, the cone is a solid object, otherwise it is a two-dimensional object in three-dimensional space. In the case of an object, the boundary formed by these lines or partial lines is called the lateral surface, if the lateral surface is unbounded. In the case of line segments, the cone does not extend beyond the base, while in the case of half-lines, in the case of lines, the cone extends infinitely far in both directions from the apex, in which case it is sometimes called a double cone. Either half of a cone on one side of the apex is called a nappe. The axis of a cone is the line, passing through the apex. If the base is right circular the intersection of a plane with this surface is a conic section, in general, the base may be any shape and the apex may lie anywhere.
Contrasted with right cones are oblique cones, in which the axis passes through the centre of the base non-perpendicularly, a cone with a polygonal base is called a pyramid. Depending on the context, cone may mean specifically a convex cone or a projective cone, cones can be generalized to higher dimensions. The perimeter of the base of a cone is called the directrix, the base radius of a circular cone is the radius of its base, often this is simply called the radius of the cone. The aperture of a circular cone is the maximum angle between two generatrix lines, if the generatrix makes an angle θ to the axis, the aperture is 2θ. A cone with a region including its apex cut off by a plane is called a cone, if the truncation plane is parallel to the cones base. An elliptical cone is a cone with an elliptical base, a generalized cone is the surface created by the set of lines passing through a vertex and every point on a boundary. The slant height of a circular cone is the distance from any point on the circle to the apex of the cone.
It is given by r 2 + h 2, where r is the radius of the cirf the cone and this application is primarily useful in determining the slant height of a cone when given other information regarding the radius or height. The volume V of any conic solid is one third of the product of the area of the base A B and the height h V =13 A B h. In modern mathematics, this formula can easily be computed using calculus – it is, up to scaling, the integral ∫ x 2 d x =13 x 3
Facets are flat faces on geometric shapes. The organization of naturally occurring facets was key to early developments in crystallography, gemstones commonly have facets cut into them in order to improve their appearance by allowing them to reflect light. Of the hundreds of arrangements that have been used, the most famous is probably the round brilliant cut, used for diamond. This first early version of what would become the modern Brilliant Cut is said to have been devised by an Italian named Peruzzi, on, the first angles for an ideal cut diamond were calculated by Marcel Tolkowsky in 1919. Slight modifications have made since then, but angles for ideal cut diamonds are still similar to Tolkowskys formula. Sometimes a 58th facet, called a culet is cut on the bottom of the stone to prevent chipping of the pavilion point. Earlier brilliant cuts often have very large culets, while modern brilliant cut diamonds generally lack the culet facet, the art of cutting a gem is an exacting procedure performed on a faceting machine.
Typically transparent to translucent stones are faceted, although opaque materials may occasionally be faceted as the luster of the gem will produce appealing reflections and black diamond are examples of opaque faceted gemstones. The angles used for each play a crucial role in the final outcome of a gem. The angles used will vary based on the index of the gem material. When light passes through a gemstone and strikes a polished facet, if the ray of light strikes a surface lower than this angle, it will leave the gem material instead of reflecting through the gem as brilliance. These lost light rays are sometimes referred to as light leakage, and this is especially common in poorly cut commercial gemstones. This machine uses a motor-driven plate to hold a precisely flat disk for the purpose of cutting or polishing, water is typically used for cutting, while either oil or water is used for the polishing process. The stone is bonded to a rod known as a dop or dop stick and is held in place by part of the mast referred to as the quill.
The dopped stone is ground at precise angles and indexes on cutting laps of progressively finer grit, accurate repetition of angles in the cutting and polishing process is aided by the angle readout and index gear. The physical process of polishing is a subject of debate, one commonly accepted theory is that the fine abrasive particles of a polishing compound produce abrasions smaller than the wavelengths of light, thus making the minute scratches invisible. Since gemstones have two sides, a device called a transfer jig is used to flip the stone so that each side may be cut. Cleaving relies on planar weaknesses of the bonds in the crystal structure of a mineral
The princess cut is the second most popular cut shape for diamonds, next to a round brilliant. The face-up shape of the cut is square or rectangular. The princess cut is a new diamond cut, having been created in the 1960s. A princess cut with the width as the diameter of a round brilliant will weigh more as it has four corners which would otherwise have been cut off. The princess cut is referred to as a square modified brilliant. However, while displaying a good degree of brilliance, its style is unique. The Barion shaped cut has now renamed the Princess cut. The ability to retain more crystal weight makes this shape popular amongst diamond cutters, accredited Gem Appraisers and American Gem Society Laboratory and European Gem Laboratories-USA are currently the only labs that grade the Princess cut for cut. Measurements vary for a cut diamond and many diamond manufacturers market ideal diamonds with differing facet patterns. The name princess cut was used in connection with another diamond cut, otherwise known as the profile cut, designed by Arpad Nagy.
The same name was used and made popular by Ygal Perlman, Betzalel Ambar. A similar cut with only 49 facets, as opposed to the original 58 facets of the cut, was branded the Quadrillion. Three years of research yielded a square stone with faceting similar to that of a round brilliant cut diamond. The number of chevrons can affect the overall outlook of a cut diamond. This can usually be determined by the diagram that is plotted in diamond grading reports. By adding more chevrons on the side of the diamond. As a result, it can give a cut diamond a crushed ice look. Vice versa, when a cut diamond has fewer chevrons
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 or organic materials that are not minerals are 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 properties that have aesthetic value. Rarity is another characteristic that lends value to a gemstone, apart from jewelry, from earliest antiquity engraved gems and hardstone carvings, such as cups, were major luxury art forms. A gem maker is called a lapidary or gemcutter, a worker is a diamantaire. The carvings of Carl Fabergé are significant works in this tradition, the traditional classification in the West, which goes back to the ancient Greeks, begins with a distinction between precious and semi-precious, similar distinctions are made in other cultures. In modern usage the precious stones are diamond, sapphire, other stones are classified by their color and hardness.
Another unscientific term for semi-precious gemstones used in art history and archaeology is hardstone, in modern times gemstones are identified by gemologists, who describe gems and their characteristics using technical terminology specific to the field of gemology. The first characteristic a gemologist uses to identify a gemstone is its chemical composition, for example, diamonds are made of carbon and rubies of aluminium oxide. Next, many gems are crystals which are classified by their crystal system such as cubic or trigonal or monoclinic, another term used is habit, the form the gem is usually found in. For example, which have a crystal system, are often found as octahedrons. Gemstones are classified into different groups and varieties, for example, ruby is the red variety of the species corundum, while any other color of corundum is considered sapphire. Other examples are the Emerald, red beryl, goshenite and morganite, gems are characterized in terms of refractive index, specific gravity, cleavage and luster.
They may exhibit pleochroism or double refraction and they may have luminescence and a distinctive absorption spectrum. Material or flaws within a stone may be present as inclusions, gemstones may be classified in terms of their water. This is a grading of the gems luster, transparency. Very transparent gems are considered first water, while second or third water gems are those of a lesser transparency, there is no universally accepted grading system for gemstones. Diamonds are graded using a system developed by the Gemological Institute of America in the early 1950s, all gemstones were graded using the naked eye
A crystal or crystalline solid is a solid material whose constituents are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macroscopic single crystals are usually identifiable by their geometrical shape, the scientific study of crystals and crystal formation is known as crystallography. The process of crystal formation via mechanisms of crystal growth is called crystallization or solidification, the word crystal derives from the Ancient Greek word κρύσταλλος, meaning both ice and rock crystal, from κρύος, icy cold, frost. Examples of large crystals include snowflakes and table salt, most inorganic solids are not crystals but polycrystals, i. e. many microscopic crystals fused together into a single solid. Examples of polycrystals include most metals, ceramics, a third category of solids is amorphous solids, where the atoms have no periodic structure whatsoever. Examples of amorphous solids include glass and many plastics, Crystals are often used in pseudoscientific practices such as crystal therapy, along with gemstones, are sometimes associated with spellwork in Wiccan beliefs and related religious movements.
The scientific definition of a crystal is based on the arrangement of atoms inside it. A crystal is a solid where the form a periodic arrangement. For example, when liquid water starts freezing, the change begins with small ice crystals that grow until they fuse. Most macroscopic inorganic solids are polycrystalline, including almost all metals, ice, solids that are neither crystalline nor polycrystalline, such as glass, are called amorphous solids, called glassy, vitreous, or noncrystalline. These have no periodic order, even microscopically, there are distinct differences between crystalline solids and amorphous solids, most notably, the process of forming a glass does not release the latent heat of fusion, but forming a crystal does. A crystal structure is characterized by its cell, a small imaginary box containing one or more atoms in a specific spatial arrangement. The unit cells are stacked in three-dimensional space to form the crystal, the symmetry of a crystal is constrained by the requirement that the unit cells stack perfectly with no gaps.
There are 219 possible crystal symmetries, called space groups. These are grouped into 7 crystal systems, such as cubic crystal system or hexagonal crystal system, Crystals are commonly recognized by their shape, consisting of flat faces with sharp angles. Euhedral crystals are those with obvious, well-formed flat faces, anhedral crystals do not, usually because the crystal is one grain in a polycrystalline solid. The flat faces of a crystal are oriented in a specific way relative to the underlying atomic arrangement of the crystal. This occurs because some surface orientations are more stable than others, as a crystal grows, new atoms attach easily to the rougher and less stable parts of the surface, but less easily to the flat, stable surfaces