A pearl is a hard glistening object produced within the soft tissue of a living shelled mollusk or another animal, such as a conulariid. Just like the shell of a mollusk, a pearl is composed of calcium carbonate in minute crystalline form, deposited in concentric layers; the ideal pearl is round and smooth, but many other shapes, known as baroque pearls, can occur. The finest quality natural pearls have been valued as gemstones and objects of beauty for many centuries; because of this, pearl has become a metaphor for something rare, fine and valuable. The most valuable pearls occur spontaneously in the wild, but are rare; these wild pearls are referred to as natural pearls. Cultured or farmed pearls from pearl oysters and freshwater mussels make up the majority of those sold. Imitation pearls are widely sold in inexpensive jewelry, but the quality of their iridescence is very poor and is distinguished from that of genuine pearls. Pearls have been harvested and cultivated for use in jewelry, but in the past were used to adorn clothing.
They have been crushed and used in cosmetics and paint formulations. Whether wild or cultured, gem-quality pearls are always nacreous and iridescent, like the interior of the shell that produces them; however all species of shelled mollusks are capable of producing pearls of lesser shine or less spherical shape. Although these may be legitimately referred to as "pearls" by gemological labs and under U. S. Federal Trade Commission rules, are formed in the same way, most of them have no value except as curiosities; the English word pearl comes from the French perle from the Latin perna meaning leg, after the ham- or mutton leg-shaped bivalve. All shelled mollusks can, by natural processes, produce some kind of "pearl" when an irritating microscopic object becomes trapped within its mantle folds, but the great majority of these "pearls" are not valued as gemstones. Nacreous pearls, the best-known and most commercially significant, are produced by two groups of molluskan bivalves or clams. A nacreous pearl is made from layers of nacre, by the same living process as is used in the secretion of the mother of pearl which lines the shell.
Natural pearls, formed without human intervention, are rare. Many hundreds of pearl oysters or mussels must be gathered and opened, thus killed, to find one wild pearl. Cultured pearls are formed in pearl farms. One family of nacreous pearl bivalves – the pearl oyster – lives in the sea, while the other – a different group of bivalves – lives in freshwater. Saltwater pearls can grow in several species of marine pearl oysters in the family Pteriidae. Freshwater pearls grow within certain species of freshwater mussels in the order Unionida, the families Unionidae and Margaritiferidae; the unique luster of pearls depends upon the reflection and diffraction of light from the translucent layers. The thinner and more numerous the layers in the pearl, the finer the luster; the iridescence that pearls display is caused by the overlapping of successive layers, which breaks up light falling on the surface. In addition, pearls can be dyed yellow, blue, pink, purple, or black; the best pearls have a metallic mirror-like luster.
Because pearls are made of calcium carbonate, they can be dissolved in vinegar. Calcium carbonate is susceptible to a weak acid solution because the crystals react with the acetic acid in the vinegar to form calcium acetate and carbon dioxide. Freshwater and saltwater pearls may sometimes look quite similar, but they come from different sources. Freshwater pearls form in various species of freshwater mussels, family Unionidae, which live in lakes, rivers and other bodies of fresh water; these freshwater pearl mussels occur not only in hotter climates, but in colder more temperate areas such as Scotland. Most freshwater cultured pearls sold. Saltwater pearls grow within family Pteriidae, which live in oceans. Saltwater pearl oysters are cultivated in protected lagoons or volcanic atolls. Pearls are formed inside the shell of certain mollusks as a defense mechanism against a threatening irritant such as a parasite inside the shell, or an attack from outside that injures the mantle tissue; the mollusk creates a pearl sac to seal off the irritation.
Pearls are thus the result of an immune response analogous in the human body to the capture of an antigen by a phagocyte. The mollusk's mantle deposits layers of calcium carbonate in the form of the mineral aragonite or a mixture of aragonite and calcite held together by an organic horn-like compound called conchiolin; the combination of aragonite and conchiolin is called nacre. The held belief that a grain of sand acts as the irritant is in fact the case. Typical stimuli include organic material, parasites, or damage that displaces mantle tissue to another part of the mollusk's body; these small particles or organisms gain entry when the shell valves are open for feeding or respiration. In cultured pearls, the irritant is an introduc
Diadem of the Stars
The Diadem of the Stars is a Diamond Tiara commissioned by Queen Consort Maria Pia of Savoy, who had a love for jewelry and fashion. It is a piece of the Portuguese Crown Jewels; the diadem was made in 1863 for the Queen Consort Maria Pia of Savoy, wife of King Luís I of Portugal. The tiara was fashioned in the workshop of the Portuguese Royal Jeweler, Estêvão de Sousa, in Lisbon, Portugal; the tiara is just a piece of a whole set of jewelry, commissioned by Maria Pia, which includes the Necklace of the Stars, the counterpart of the diadem. The Diadem of the Stars was made in the workshop of the Portuguese Royal Jeweler in Lisbon, Portugal. Commissioned in 1863, the tiara took three years before it was completed in 1866, it is fashioned out of gold and colourless and pink diamonds. Jóias da Coroa Portuguesa
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 and polish of a diamond; the cut of a diamond affects a diamond's brilliance. In order to best use a diamond gemstone's 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, when choosing a cut; 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. Design creation and innovation continue to the present day: new technology—notably laser cutting and computer-aided design—has enabled the development of cuts whose complexity, optical performance, waste reduction were hitherto unthinkable.
The most popular of diamond cuts is the modern round brilliant, whose facet arrangements and proportions have been perfected by both mathematical and empirical analysis. Popular are the fancy cuts, which come in a variety of shapes, many of which were derived from the round brilliant. A diamond's cut is evaluated by trained graders, with higher grades given to stones whose symmetry and proportions most match the particular "ideal" used as a benchmark; the strictest standards are applied to the round brilliant. 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, before which time diamonds were employed in their natural octahedral state—anhedral diamonds were not used in jewelry. The first "improvements" on nature's design involved a simple polishing of the octahedral crystal faces to create and unblemished facets, or to fashion the desired octahedral shape out of an otherwise unappealing piece of rough.
This was called the point cut and dates from the mid 14th century. By the mid 15th century, the point cut began to be improved upon: a little less than one half of the octahedron would be sawn off, creating the table cut; the importance of a culet was realised, 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. At the time, diamond was valued chiefly for its adamantine 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 shape known as briolette. About the middle of the 16th century, the rose or rosette was introduced in Antwerp: it consisted of triangular facets arranged in a symmetrical radiating pattern, but with the bottom of the stone left flat—essentially a crown without a pavilion.
Many large, famous Indian diamonds of old feature a rose-like cut. However, Indian "rose cuts" were far less symmetrical as their cutters had the primary interest of conserving carat weight, due to the divine status of diamond in India. 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. Vincent Peruzzi, a Venetian polisher increased the number of crown facets from 17 to 33, thereby increasing the fire and brilliance of the cut gem, properties that in the Mazarin were incomparably better than in the rose, yet Peruzzi-cut diamonds, when seen nowadays, seem exceedingly dull compared to modern-cut brilliants. Because the practice of bruting had not yet been developed, these early brilliants were all rounded squares or rectangles in cross-section.
Given the general name of cushion—what are known today as old mine cuts—these were common by the early 18th century. Sometime the old European cut was developed, which had a shallower pavilion, more rounded shape, different arrangement of facets; the old European cut was the forerunner of modern brilliants and was the most advanced in use during the 19th century. Around 1900, the development of diamond saws and good jewelry lathes enabled the development of modern diamond cutting and diamond cuts, chief among them the round brilliant cut. In 1919, Marcel Tolkowsky analyzed this cut: his calculations took both brilliance and fire into consideration, creating a delicate balance between the two. Tolkowsky's calculations would serve as the basis for all future brilliant cut modifications and standards. Tolkowsky's model of the "ideal" cut is not perfect; the original mo
Portuguese Crown Jewels
The Portuguese Crown Jewels were the pieces of jewelry and vestments worn by the Monarchs of Portugal during the time of the Portuguese Monarchy. Over the nine centuries of Portuguese history, the Portuguese Crown Jewels have lost and gained many pieces. Most of the current set of the Portuguese Crown Jewels are from the reigns of King João VI and King Luís I. By the reign of King Manuel I, Portugal had a lavish set of jewels, the king having been one of the most powerful men in the world at the time and having been known to show off. In early 1581 King António I fled to France after King Philip I was made the King of Portugal. António I took with him the Portuguese Crown Jewels, including many valuable diamonds. Being well received by the French Queen Consort, Catherine de' Medici, he sold her some of the pieces of the Portuguese Crown Jewels in return for France's support in his plans to reclaim the throne of Portugal and depose Philip I. After several failed attempts to reclaim the Portuguese Crown, António I fell into poverty.
His poverty led him to sell many of the remaining diamonds. The last and finest diamond of the Portuguese Crown Jewels, the Sancy, would be acquired by Nicolas de Harlay, seigneur de Sancy, from whom it would make its way to Maximilien de Béthune, duc de Sully. From Maximilien, the diamond would go to join the French Crown Jewels. During the Portuguese Restoration War, João II of Braganza sold many of the Portuguese Crown Jewels to finance the war with Spain; when João II became King of Portugal as João IV and deposed the Philippine Dynasty in 1640, he placed his crown with a statue of Our Lady of Immaculate Conception and said that she was the "true Queen of Portugal". Since Portuguese monarchs did not have a coronation but instead an acclamation. Before the assumption of the Portuguese throne by the Philippine Dynasty, the Kings of Portugal used to be anointed and crowned in the Jeronimos Monastery in Lisbon. In 1755 the Great Lisbon earthquake destroyed Lisbon and the Paço da Ribeira, the Portuguese royal residence of the time.
With the destruction of the palace, innumerable pieces of the Portuguese Crown Jewels of the time were destroyed, lost, or stolen. While his court was in Rio de Janeiro, João VI had a new set of Portuguese Crown Jewels made. Constructed by the royal jewelers at the workshop of António Gomes da Silva, the set most notably included a new crown and sceptre, among a plethora of jewelry pieces; the pieces from this era are the majority of the current set of jewels. When Maria Pia of Savoy became Queen Consort of Portugal, King Luís I ordered many pieces of jewelry to be made, as it was a passion of his wife. Alongside this, he had a new royal mantle produced; when the Portuguese Royal Family was exiled, many of the jewels were taken with Queen Amélie of Orléans and Queen Mother Maria Pia of Savoy on their respective exiles. In 2002 a large part of the Portuguese Crown Jewels were stolen from the Museon in The Hague, where they were on loan for an exhibition on European Crown Jewels. Following an investigation by the museum and Dutch authorities, the Dutch government paid a sum of six million euros to the Portuguese government for reparation.
The Portuguese Crown Jewels are kept in a secured vault at the Ajuda National Palace, in Lisbon. While the palace is a popular and important museum, the crown jewels are not open to the public; the crown jewels are now only seen at special events concerning them or the palace a repercussion of the 2002 Hague theft. Though the Portuguese Crown Jewels have had a long history, wars and devastation have reduced the jewels to those produced under the reigns of João VI and Luís I; the current set of crown jewels includes numerous pieces of jewelry, gems and other regalia, but most notably: The Crown of João VI is an imperial format crown. A unique feature of the crown is that it is composed only of pure gold and red velvet, without a single precious stone or gem — an oddity amongst European crowns of the time; the crown was made in 1817 for the acclamation of King João VI. It was created in the workshop of Dom António Gomes da Silva, in Rio de Janeiro; the Sceptre of the Armillary is the sceptre, created for the acclamation of King João VI, in the workshop of the Royal Jeweler, Dom António Gomes da Silva, in Rio de Janeiro.
The sceptre bears the symbols of the United Kingdom of Portugal and the Algarve, Portugal's designation during João VI's stay in Brazil. The Mantle of João VI is the royal robe, fashioned for the acclamation of King João VI; the mantle was fashioned in Portugal though João VI's court was in Brazil. The royal robe bears many symbols of the Kingdom of Portugal and was only used by João VI; the Sceptre of the Dragon is the sceptre, created for the acclamation and use of Queen Maria II, in London, England. The sceptre bears many symbols pertaining to Portugal's new constitution, though Portugal would commence its War of the Two Brothers the year the sceptre was created; the Mantle of Luís I is the royal robe, fashioned for the acclamation of King Luís I. The mantle bears many symbols of the Kingdom of Portugal. Though made for Luís I, it was used by all the monarchs of Portugal afterwards; the Diadem of the Stars is a famous Portuguese diamond tiara. It was commissioned by the Consort of Queen Maria Pia of Savoy.
The tiara is just a piece of a whole set of jewelry, famed for its precious diamonds and sapphires, commissioned by Maria Pia, famous for her love in the arts of fashion and jewelry. The Necklace of the Stars is a famous diamond necklace, it was commissioned by Queen Maria Pia of Savoy, the Consort of King Luís I. The necklace is a piece the set of jewelry commissi
Diamond is a solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. At room temperature and pressure, another solid form of carbon known as graphite is the chemically stable form, but diamond never converts to it. Diamond has the highest hardness and thermal conductivity of any natural material, properties that are utilized in major industrial applications such as cutting and polishing tools, they are the reason that diamond anvil cells can subject materials to pressures found deep in the Earth. Because the arrangement of atoms in diamond is rigid, few types of impurity can contaminate it. Small numbers of defects or impurities color diamond blue, brown, purple, orange or red. Diamond has high optical dispersion. Most natural diamonds have ages between 1 billion and 3.5 billion years. Most were formed at depths between 150 and 250 kilometers in the Earth's mantle, although a few have come from as deep as 800 kilometers. Under high pressure and temperature, carbon-containing fluids dissolved minerals and replaced them with diamonds.
Much more they were carried to the surface in volcanic eruptions and deposited in igneous rocks known as kimberlites and lamproites. Synthetic diamonds can be grown from high-purity carbon under high pressures and temperatures or from hydrocarbon gas by chemical vapor deposition. Imitation diamonds can be made out of materials such as cubic zirconia and silicon carbide. Natural and imitation diamonds are most distinguished using optical techniques or thermal conductivity measurements. Diamond is a solid form of pure carbon with its atoms arranged in a crystal. Solid carbon comes in different forms known as allotropes depending on the type of chemical bond; the two most common allotropes of pure carbon are graphite. In graphite the bonds are sp2 orbital hybrids and the atoms form in planes with each bound to three nearest neighbors 120 degrees apart. In diamond they are sp3 and the atoms form tetrahedra with each bound to four nearest neighbors. Tetrahedra are rigid, the bonds are strong, of all known substances diamond has the greatest number of atoms per unit volume, why it is both the hardest and the least compressible.
It has a high density, ranging from 3150 to 3530 kilograms per cubic metre in natural diamonds and 3520 kg/m³ in pure diamond. In graphite, the bonds between nearest neighbors are stronger but the bonds between planes are weak, so the planes can slip past each other. Thus, graphite is much softer than diamond. However, the stronger bonds make graphite less flammable. Diamonds have been adapted for many uses because of the material's exceptional physical characteristics. Most notable are its extreme hardness and thermal conductivity, as well as wide bandgap and high optical dispersion. Diamond's ignition point is 720 -- 800 °C in 850 -- 1000 °C in air; the equilibrium pressure and temperature conditions for a transition between graphite and diamond is well established theoretically and experimentally. The pressure changes linearly between 1.7 GPa at 0 K and 12 GPa at 5000 K. However, the phases have a wide region about this line where they can coexist. At normal temperature and pressure, 20 °C and 1 standard atmosphere, the stable phase of carbon is graphite, but diamond is metastable and its rate of conversion to graphite is negligible.
However, at temperatures above about 4500 K, diamond converts to graphite. Rapid conversion of graphite to diamond requires pressures well above the equilibrium line: at 2000 K, a pressure of 35 GPa is needed. Above the triple point, the melting point of diamond increases with increasing pressure. At high pressures and germanium have a BC8 body-centered cubic crystal structure, a similar structure is predicted for carbon at high pressures. At 0 K, the transition is predicted to occur at 1100 GPa; the most common crystal structure of diamond is called diamond cubic. It is formed of unit cells stacked together. Although there are 18 atoms in the figure, each corner atom is shared by eight unit cells and each atom in the center of a face is shared by two, so there are a total of eight atoms per unit cell; each side of the unit cell is 3.57 angstroms in length. A diamond cubic lattice can be thought of as two interpenetrating face-centered cubic lattices with one displaced by 1/4 of the diagonal along a cubic cell, or as one lattice with two atoms associated with each lattice point.
Looked at from a <1 1 1> crystallographic direction, it is formed of layers stacked in a repeating ABCABC... pattern. Diamonds can form an ABAB... structure, known as hexagonal diamond or lonsdaleite, but this is far less common and is formed under different conditions from cubic carbon. Diamonds occur most as euhedral or rounded octahedra and twinned octahedra known as macles; as diamond's crystal structure has a cubic arrangement of the atoms, they have many facets that belong to a cube, rhombicosidodecahedron, tetrakis hexahedron or disdyakis dodecahedron. The crystals can be elongated. Diamonds are found coated in nyf, an opaque gum-like skin; some diamonds have opaque fibers. They are referred to as opaque if the fibers
The Smithsonian Institution, founded on August 10, 1846 "for the increase and diffusion of knowledge," is a group of museums and research centers administered by the Government of the United States. The institution is named after British scientist James Smithson. Organized as the "United States National Museum," that name ceased to exist as an administrative entity in 1967. Termed "the nation's attic" for its eclectic holdings of 154 million items, the Institution's nineteen museums, nine research centers, zoo include historical and architectural landmarks located in the District of Columbia. Additional facilities are located in Arizona, Massachusetts, New York City, Texas and Panama. More than 200 institutions and museums in 45 states, Puerto Rico, Panama are Smithsonian Affiliates; the Institution's thirty million annual visitors are admitted without charge. Its annual budget is around $1.2 billion with two-thirds coming from annual federal appropriations. Other funding comes from the Institution's endowment and corporate contributions, membership dues, earned retail and licensing revenue.
Institution publications include Air & Space magazines. The British scientist James Smithson left most of his wealth to his nephew Henry James Hungerford; when Hungerford died childless in 1835, the estate passed "to the United States of America, to found at Washington, under the name of the Smithsonian Institution, an Establishment for the increase & diffusion of knowledge among men", in accordance with Smithson's will. Congress accepted the legacy bequeathed to the nation, pledged the faith of the United States to the charitable trust on July 1, 1836; the American diplomat Richard Rush was dispatched to England by President Andrew Jackson to collect the bequest. Rush returned in August 1838 with 105 sacks containing 104,960 gold sovereigns. Once the money was in hand, eight years of Congressional haggling ensued over how to interpret Smithson's rather vague mandate "for the increase and diffusion of knowledge." The money was invested by the US Treasury in bonds issued by the state of Arkansas, which soon defaulted.
After heated debate, Massachusetts Representative John Quincy Adams persuaded Congress to restore the lost funds with interest and, despite designs on the money for other purposes, convinced his colleagues to preserve it for an institution of science and learning. On August 10, 1846, President James K. Polk signed the legislation that established the Smithsonian Institution as a trust instrumentality of the United States, to be administered by a Board of Regents and a Secretary of the Smithsonian. Though the Smithsonian's first Secretary, Joseph Henry, wanted the Institution to be a center for scientific research, it became the depository for various Washington and U. S. government collections. The United States Exploring Expedition by the U. S. Navy circumnavigated the globe between 1838 and 1842; the voyage amassed thousands of animal specimens, an herbarium of 50,000 plant specimens, diverse shells and minerals, tropical birds, jars of seawater, ethnographic artifacts from the South Pacific Ocean.
These specimens and artifacts became part of the Smithsonian collections, as did those collected by several military and civilian surveys of the American West, including the Mexican Boundary Survey and Pacific Railroad Surveys, which assembled many Native American artifacts and natural history specimens. In 1846, the regents developed a plan for weather observation; the Institution became a magnet for young scientists from 1857 to 1866, who formed a group called the Megatherium Club. The Smithsonian played a critical role as the U. S. partner institution in early bilateral scientific exchanges with the Academy of Sciences of Cuba. Construction began on the Smithsonian Institution Building in 1849. Designed by architect James Renwick Jr. its interiors were completed by general contractor Gilbert Cameron. The building opened in 1855; the Smithsonian's first expansion came with construction of the Arts and Industries Building in 1881. Congress had promised to build a new structure for the museum if the 1876 Philadelphia Centennial Exposition generated enough income.
It did, the building was designed by architects Adolf Cluss and Paul Schulze, based on original plans developed by Major General Montgomery C. Meigs of the United States Army Corps of Engineers, it opened in 1881. The National Zoological Park opened in 1889 to accommodate the Smithsonian's Department of Living Animals; the park was designed by landscape architect Frederick Law Olmsted. The National Museum of Natural History opened in June 1911 to accommodate the Smithsonian's United States National Museum, housed in the Castle and the Arts and Industries Building; this structure was designed by the D. C. architectural firm of Hornblower & Marshall. When Detroit philanthropist Charles Lang Freer donated his private collection to the Smithsonian and funds to build the museum to hold it, it was among the Smithsonian's first major donations from a private individual; the gallery opened in 1923. More than 40 years would pass before the next museum, the Museum of History and Technology, opened in 1964.
It was designed by the world-renowned firm of Mead & White. The Anacostia Community Museum, an "experimental store-front" museum created at the initiative of Smithsonian Secretary S. Dillon Ripley, opened in the Anacostia neighborhood of
Sceptre of the Dragon
The Sceptre of the Dragon known as the Sceptre of the Crown and Constitution, is a piece of the Portuguese Crown Jewels created for the acclamation of Queen Maria II. The Sceptre of the Dragon was made of pure gold, in London, England; the Sceptre of the Dragon, along with all the other Portuguese Crown Jewels, are kept in the Ajuda National Palace, though they are not on display to the public. The sceptre bears several symbols of the Kingdom of Portugal: Crown of João VI - The crown of the monarchs of Portugal and a symbol of the monarchy's power and authority Portuguese Constitution of 1826 - The constitution of Portugal, which returned Portugal to a constitutional monarchy and symbolizes the power that people hold under the new regime Dragon - The wyvern, emblem of the House of Braganza the royal house of Portugal Sceptre of the Armillary Jóias da Coroa Portuguesa