Tower of London
The Tower of London Her Majesty's Royal Palace and Fortress of the Tower of London, is a historic castle located on the north bank of the River Thames in central London. It lies within the London Borough of Tower Hamlets, separated from the eastern edge of the square mile of the City of London by the open space known as Tower Hill, it was founded towards the end of 1066 as part of the Norman Conquest of England. The White Tower, which gives the entire castle its name, was built by William the Conqueror in 1078 and was a resented symbol of oppression, inflicted upon London by the new ruling elite; the castle was used as a prison from 1100 until 1952, although, not its primary purpose. A grand palace early in its history, it served as a royal residence; as a whole, the Tower is a complex of several buildings set within two concentric rings of defensive walls and a moat. There were several phases of expansion under Kings Richard I, Henry III, Edward I in the 12th and 13th centuries; the general layout established by the late 13th century remains despite activity on the site.
The Tower of London has played a prominent role in English history. It was besieged several times, controlling it has been important to controlling the country; the Tower has served variously as an armoury, a treasury, a menagerie, the home of the Royal Mint, a public record office, the home of the Crown Jewels of England. From the early 14th century until the reign of Charles II, a procession would be led from the Tower to Westminster Abbey on the coronation of a monarch. In the absence of the monarch, the Constable of the Tower is in charge of the castle; this was a trusted position in the medieval period. In the late 15th century, the castle was the prison of the Princes in the Tower. Under the Tudors, the Tower became used less as a royal residence, despite attempts to refortify and repair the castle, its defences lagged behind developments to deal with artillery; the peak period of the castle's use as a prison was the 16th and 17th centuries, when many figures who had fallen into disgrace, such as Elizabeth I before she became queen, Sir Walter Raleigh, Elizabeth Throckmorton, were held within its walls.
This use has led to the phrase "sent to the Tower". Despite its enduring reputation as a place of torture and death, popularised by 16th-century religious propagandists and 19th-century writers, only seven people were executed within the Tower before the World Wars of the 20th century. Executions were more held on the notorious Tower Hill to the north of the castle, with 112 occurring there over a 400-year period. In the latter half of the 19th century, institutions such as the Royal Mint moved out of the castle to other locations, leaving many buildings empty. Anthony Salvin and John Taylor took the opportunity to restore the Tower to what was felt to be its medieval appearance, clearing out many of the vacant post-medieval structures. In the First and Second World Wars, the Tower was again used as a prison and witnessed the executions of 12 men for espionage. After the Second World War, damage caused during the Blitz was repaired, the castle reopened to the public. Today, the Tower of London is one of the country's most popular tourist attractions.
Under the ceremonial charge of the Constable of the Tower, operated by the Resident Governor of the Tower of London and Keeper of the Jewel House, the property is cared for by the charity Historic Royal Palaces and is protected as a World Heritage Site. The Tower was orientated with its strongest and most impressive defences overlooking Saxon London, which archaeologist Alan Vince suggests was deliberate, it stood out to traffic on the River Thames. The castle enclosures; the innermost ward is the earliest phase of the castle. Encircling it to the north and west is the inner ward, built during the reign of Richard I. There is the outer ward which encompasses the castle and was built under Edward I. Although there were several phases of expansion after William the Conqueror founded the Tower of London, the general layout has remained the same since Edward I completed his rebuild in 1285; the castle encloses an area of 12 acres with a further 6 acres around the Tower of London constituting the Tower Liberties – land under the direct influence of the castle and cleared for military reasons.
The precursor of the Liberties was laid out in the 13th century when Henry III ordered that a strip of land adjacent to the castle be kept clear. Despite popular fiction, the Tower of London never had a permanent torture chamber, although the basement of the White Tower housed a rack in periods. Tower Wharf was built on the bank of the Thames under Edward I and was expanded to its current size during the reign of Richard II; the White Tower is a keep, the strongest structure in a medieval castle, contained lodgings suitable for the lord – in this case, the king or his representative. According to military historian Allen Brown, "The great tower was by virtue of its strength and lordly accommodation, the donjon par excellence"; as one of the largest keeps in the Christian world, the White Tower has been described as "the most complete eleventh-century palace in Europe". The White Tower, not including its projecting corner towers, measures 36 by 32 metres at the base, is 27 m high at the southern battlements.
The structure was three storeys high, comprising a basement floor, an entrance level, an upper floor. The entrance, as is usual in Norman keeps, was above ground
A chemically pure and structurally perfect diamond is transparent with no hue, or color. However, in reality no gem-sized natural diamonds are perfect; the color of a diamond may be affected by chemical impurities and/or structural defects in the crystal lattice. Depending on the hue and intensity of a diamond's coloration, a diamond's color can either detract from or enhance its value. For example, most white diamonds are discounted in price when more yellow hue is detectable, while intense pink diamonds or blue diamonds can be more valuable. Of all colored diamonds, red diamonds are the rarest; the Aurora Pyramid of Hope displays a spectacular array of colored diamonds, including red diamonds. Diamonds occur in a variety of colors—steel gray, blue, orange, green, pink to purple and black. Colored diamonds contain interstitial impurities or structural defects that cause the coloration, pure diamonds are transparent and colorless. Diamonds are scientifically classed into two main types and several subtypes, according to the nature of impurities present and how these impurities affect light absorption: Type I diamonds have nitrogen atoms as the main impurity at a concentration of 0.1%.
If the nitrogen atoms are in pairs they do not affect the diamond's color. If the nitrogen atoms are in large even-numbered aggregates they impart a yellow to brown tint. About 98% of gem diamonds are type Ia, most of these are a mixture of IaA and IaB material: these diamonds belong to the Cape series, named after the diamond-rich region known as Cape Province in North Africa, whose deposits are Type Ia. If the nitrogen atoms are dispersed throughout the crystal in isolated sites, they give the stone an intense yellow or brown tint. Synthetic diamond containing nitrogen is Type Ib. Type I diamonds absorb from 320 nm, they have a characteristic fluorescence and visible absorption spectrum. Type II diamonds have no measurable nitrogen impurities. Type II diamonds absorb in a different region of the infrared, transmit in the ultraviolet below 225 nm, unlike Type I diamonds, they have differing fluorescence characteristics, but no discernible visible absorption spectrum. Type IIa diamond can be colored pink, red, or brown due to structural anomalies arising through plastic deformation during crystal growth—these diamonds are rare, but constitute a large percentage of Australian production.
Type IIb diamonds, which account for 0.1% of gem diamonds, are light blue due to scattered boron within the crystal matrix. However, a blue-grey color may occur in Type Ia diamonds and be unrelated to boron. Not restricted to type are green diamonds, whose color is caused by GR1 color centers in the crystal lattice produced by exposure to varying quantities of radiation. Pink and red are caused by plastic deformation of the crystal lattice from pressure. Black diamonds are caused by microscopic black or gray inclusions of other materials such as graphite or sulfides and/or microscopic fractures. Opaque or opalescent white diamonds are caused by microscopic inclusions. Purple diamonds are caused by a combination of high hydrogen content; the majority of diamonds that are mined are in a range of pale yellow or brown color, termed the normal color range. Diamonds that are of intense yellow or brown, or any other color are called fancy color diamonds. Diamonds that are of the highest purity are colorless, appear a bright white.
The degree to which diamonds exhibit body color is one of the four value factors by which diamonds are assessed. Diamonds have a color grading system; this system goes from D to Z. The more colorless a diamond is, the rarer and more valuable it is because it appears white and brighter to the eye. Color grading of diamonds was performed as a step of sorting rough diamonds for sale by the London Diamond Syndicate; as the diamond trade developed, early diamond grades were introduced by various parties in the diamond trade. Without any co-operative development these early grading systems lacked standard nomenclature, consistency; some early grading scales were. Numerous terms developed to describe diamonds of particular colors: golconda, jagers, blue white, fine white, gem blue, etc. Refers to a grading scale for diamonds in the normal color range used by internationally recognized laboratories; the scale ranges from D, colorless to Z, a pale yellow or brown color. Brown diamonds darker than K color are described using their letter grade, a descriptive phrase, for example M Faint Brown.
Diamonds with more depth of color than Z color fall into the fancy color diamond range. Diamond color is graded by comparing a sample stone to a master stone set of diamonds; each master stone is known to exhibit the least amount of body color that a diamond in that color grade may exhibit. A trained diamond grader compares a diamond of unknown grade against the series of master stones, assessing where in the range of color the diamond resides; this process occurs in a lighting box, fitted with daylight equivalent lamps. Accurate color grading can only be performed with diamond unset, as the comparison with master
The Cullinan Diamond was the largest gem-quality rough diamond found, weighing 3,106.75 carats, discovered at the Premier No. 2 mine in Cullinan, South Africa, on 26 January 1905. It was named after the mine's chairman. In April 1905, it was put on sale in London, but despite considerable interest, it was still unsold after two years. In 1907 the Transvaal Colony government bought the Cullinan and presented it to Edward VII, King of the United Kingdom, who had it cut by Asscher Brothers in Amsterdam. Cullinan produced stones of various cuts and sizes, the largest of, named Cullinan I or the Great Star of Africa, at 530.4 carats it is the largest clear cut diamond in the world. The stone is mounted in the head of the Sovereign's Sceptre with Cross; the second-largest is Cullinan II or the Second Star of Africa, weighing 317.4 carats, mounted in the Imperial State Crown. Both are part of the Crown Jewels. Seven other major diamonds, weighing a total of 208.29 carats, are owned by Elizabeth II, who inherited them from her grandmother, Queen Mary, in 1953.
The Queen owns minor brilliants and a set of unpolished fragments. The Cullinan is estimated to have formed in Earth's mantle transition zone at a depth of 410–660 km and reached the surface 1.18 billion years ago. It was found 18 feet below the surface at Premier Mine in Cullinan, Transvaal Colony, by Frederick Wells, surface manager at the mine, on 26 January 1905, it was 10.1 centimetres long, 6.35 centimetres wide, 5.9 centimetres deep, weighed 3,106 carats. Newspapers called it the "Cullinan Diamond", a reference to Sir Thomas Cullinan, who opened the mine in 1902, it was three times the size of the Excelsior Diamond, found in 1893 at Jagersfontein Mine, weighing 972 carats. Four of its eight surfaces were smooth, indicating that it once had been part of a much larger stone broken up by natural forces, it had a blue-white hue and contained a small pocket of air, which at certain angles produced a rainbow, or Newton's rings. Shortly after its discovery, Cullinan went on public display at the Standard Bank in Johannesburg, where it was seen by an estimated 8,000–9,000 visitors.
In April 1905, the rough gem was deposited with Premier Mining Co.'s London sales agent, S. Neumann & Co. Due to its immense value, detectives were assigned to a steamboat, rumoured to be carrying the stone, a parcel was ceremoniously locked in the captain's safe and guarded on the entire journey, it was a diversionary tactic – the stone on that ship was fake, meant to attract those who would be interested in stealing it. Cullinan was sent to the United Kingdom in a plain box via registered post. On arriving in London, it was conveyed to Buckingham Palace for inspection by King Edward VII, it drew considerable interest from potential buyers. Transvaal Prime Minister, Louis Botha, suggested buying the diamond for Edward VII as "a token of the loyalty and attachment of the people of the Transvaal to His Majesty's throne and person". In August 1907, a vote was held in Parliament on the Cullinan's fate, a motion authorising the purchase was carried by 42 votes in favour to 19 against. Henry Campbell-Bannerman British Prime Minister, advised the king to decline the offer, but he decided to let Edward VII choose whether or not to accept the gift.
He was persuaded by Winston Churchill Colonial Under-Secretary. For his trouble, Churchill was sent a replica, which he enjoyed showing off to guests on a silver plate; the Transvaal Colony government bought the diamond on 17 October 1907 for £150,000 or about US$750,000 at the time, which adjusted for pound-sterling inflation is equivalent to £15 million in 2016. Due to a 60% tax on mining profits, the Treasury received some of its money back from the Premier Diamond Mining Company; the diamond was presented to the king at Sandringham House on 9 November 1907 – his sixty-sixth birthday – in the presence of a large party of guests, including the Queen of Norway, the Queen of Spain, the Duke of Westminster and Lord Revelstoke. The king asked his colonial secretary, Lord Elgin, to announce that he accepted the gift "for myself and my successors" and that he would ensure "this great and unique diamond be kept and preserved among the historic jewels which form the heirlooms of the Crown"; the king chose Asscher Brothers of Amsterdam to cleave and polish the rough stone into brilliant gems of various cuts and sizes.
Abraham Asscher collected it from the Colonial Office in London on 23 January 1908. He returned to the Netherlands by ferry with the diamond in his coat pocket. Meanwhile, to much fanfare, a Royal Navy ship carried an empty box across the North Sea, again throwing off potential thieves; the captain had no idea that his "precious" cargo was a decoy. On 10 February 1908, the rough stone was split in half by Joseph Asscher at his diamond-cutting factory in Amsterdam. At the time, technology had not yet evolved to guarantee the quality of modern standards, cutting the diamond was difficult and risky. After weeks of planning, an incision 0.5 inches deep was made to enable Asscher to cleave the diamond in one blow. Making the incision alone took four days, a steel knife broke on the first attempt, but a second knife was fitted into the groove and split it clean in two along one of four possible cleavage planes. In all and cutting the diamond took eight months, with three people working 14 hours per day to complete the task."The tale is told of Joseph Asscher, the greatest cleaver of the day," wrote Matthew Hart in his book Diamond: A Journey to the Heart of an Obsession, "that when he prepared to cleave
The Premier Mine is an underground diamond mine owned by Petra Diamonds in the town of Cullinan, 40 kilometres east of Pretoria, Gauteng Province, South Africa. Established in 1902, it was renamed the Cullinan Diamond Mine in November 2003 in celebration of its centenary; the mine rose to prominence in 1905, when the Cullinan Diamond – the largest rough diamond of gem quality found – was discovered there. The mine has produced over 750 stones that are greater than 100 carats and more than a quarter of all the world's diamonds that are greater than 400 carats, it is the only significant source of blue diamonds in the world. The Cullinan Diamond is the largest rough gem-quality diamond found, at 3,106.75 carats. It was found by Frederick Wells, surface manager of the Premier Diamond Mining Company in Cullinan, South Africa, on 25 January 1905; the stone was named after the owner of the diamond mine. There have been various other notable diamonds; these include: The Premier Rose – 353 carats rough The Niarchos – 426 carats rough The De Beers Centenary – 275 carats rough Golden Jubilee Diamond – 755 carats rough Taylor-Burton Diamond – 69 carats polishedThe Cullinan Heritage—507 carats rough—was recovered from the same mine.
In February 2010, it was sold for USD 35.3 million. Until now, this is the highest price on record for a rough diamond. In May 2008, a sparkling shield-shaped 101.27-carat diamond mined from the Premier Mine sold for more than US$6.2 million at Christie's in Hong Kong. Cut from a 460 carats rough, the shield-shaped gem boasts 92 brilliant facets. While internally flawless, the stone has a slight imperfection on the surface, imperceptible to the human eye, the auction house said, it is the largest colourless diamond to appear on the auction market in the last 18 years, Christie's said. Only three diamonds of more than 100 carats have appeared at auction. All were sold in Geneva. Naming rights were granted to the new owner. In September 2009, a 507-carat diamond was found, is ranked as one of the 20 biggest high quality diamonds discovered. Petra Diamonds sold it for $35.3 million on 26 February 2010, breaking a record as the highest price paid for a rough diamond. On 18 April 2013 a 25.5-carat blue rough diamond was recovered by Petra Diamonds at its Cullinan mine.
According to experts it could be worth more than $10m. The find; the mine is famed for its production of blue diamonds. A similar 26.6-carat blue rough diamond recovered by Petra in May 2009 was cut into a near perfect stone and fetched just under $10m at Sotheby's. Another deep-blue diamond from Cullinan was auctioned for $10.8m last year and set a world record for the value per carat. On 21 January 2014, Petra Diamonds announced recovery of a 29.6-carat blue diamond. According to the current CEO, Johan Dippenaar, it is one the "most significant blue diamond" to be recovered by Petra Diamonds. According to Analyst Cailey Barker at broker Numis it "could fetch between $15m and $20m at auction". Decision on what is to be done with the stone will come next week. On 13 June 2014, Petra Diamonds announced that a blue diamond of 122.52 carats was found at the Cullinan mine. The diamond, though not yet appraised, is expected to fetch more than 35 million dollars, the approximate value of the Heritage Diamond found in that mine.
Petra Diamonds says that the diamond will not be put up for auction before their fiscal year ends this month. Cullinan Diamond Mine is a carrot has a surface area of 32 hectares. On 22 November 2007, De Beers, the world's largest diamond producer, sold its historic Cullinan mine to Petra Diamonds Cullinan Consortium, a consortium led by Petra Diamonds. Diamond Mines of South Africa, Premier Diamond mine overview + images by A. R. Williams former general manager of De Beers. De Beers sells South African Cullinan Diamond Mine Official website
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