The Yellow River or Huang He is the second longest river in China, after the Yangtze River, the sixth longest river system in the world at the estimated length of 5,464 km. Originating in the Bayan Har Mountains in Qinghai province of Western China, it flows through nine provinces, it empties into the Bohai Sea near the city of Dongying in Shandong province; the Yellow River basin has an east–west extent of about 1,900 kilometers and a north–south extent of about 1,100 km. Its total drainage area is about 752,546 square kilometers, its basin was the birthplace of ancient Chinese civilization, it was the most prosperous region in early Chinese history. There are frequent devastating floods and course changes produced by the continual elevation of the river bed, sometimes above the level of its surrounding farm fields. Early Chinese literature including the Yu Gong or Tribute of Yu dating to the Warring States period refers to the Yellow River as 河, a character that has come to mean "river" in modern usage.
The first appearance of the name 黃河 is in the Book of Han written during the Eastern Han dynasty about the Western Han dynasty. The adjective "yellow" describes the perennial color of the muddy water in the lower course of the river, which arises from soil being carried downstream. One of its older Mongolian names was the "Black River", because the river runs clear before it enters the Loess Plateau, but the current name of the river among Inner Mongolians is Ȟatan Gol. In Mongolia itself, it is called the Šar Mörön. In Qinghai, the river's Tibetan name is "River of the Peacock" The Yellow River is one of several rivers that are essential for China's existence. At the same time, however, it has been responsible for several deadly floods, including the only natural disasters in recorded history to have killed more than a million people; the deadliest was a Yuan dynasty 1332 -- 33 flood. Close behind during the Qing dynasty is the 1887 flood, which killed anywhere from 900,000 to 2 million people, a Republic of China era 1931 flood that killed 1–4 million people.
The cause of the floods is the large amount of fine-grained loess carried by the river from the Loess Plateau, continuously deposited along the bottom of its channel. The sedimentation causes natural dams to accumulate; these subaqueous dams were unpredictable and undetectable. The enormous amount of water has to find a new way to the sea, forcing it to take the path of least resistance; when this happens, it bursts out across the flat North China Plain, sometimes taking a new channel and inundating any farmland, cities or towns in its path. The traditional Chinese response of building higher and higher levees along the banks sometimes contributed to the severity of the floods: When flood water did break through the levees, it could no longer drain back into the river bed as it would after a normal flood as the river bed was sometimes now higher than the surrounding countryside; these changes could cause the river's mouth to shift as much as 480 km, sometimes reaching the ocean to the north of Shandong Peninsula and sometimes to the south.
Another historical source of devastating floods is the collapse of upstream ice dams in Inner Mongolia with an accompanying sudden release of vast quantities of impounded water. There have been 11 such major floods in the past century, each causing tremendous loss of life and property. Nowadays, explosives dropped from aircraft are used to break the ice dams before they become dangerous. Before modern dams came to China, the Yellow River used to be prone to flooding. In the 2,540 years from 595 BC to 1946 AD, the Yellow River has been reckoned to have flooded 1,593 times, shifting its course 26 times noticeably and nine times severely; these floods include some of the deadliest natural disasters recorded. Before modern disaster management, when floods occurred, some of the population might die from drowning but many more would suffer from the ensuing famine and spread of diseases. In Chinese mythology, the giant Kua Fu drained the Yellow River and the Wei River to quench his burning thirst as he pursued the Sun.
Historical documents from the Spring and Autumn period and Qin dynasty indicate that the Yellow River at that time flowed north of its present course. These accounts show that after the river passed Luoyang, it flowed along the border between Shanxi and Henan Provinces continued along the border between Hebei and Shandong before emptying into Bohai Bay near present-day Tianjin. Another outlet followed the present course; the river left these paths in 602 BC and shifted south of the Shandong Peninsula. Sabotage of dikes and reservoirs and deliberate flooding of rival states became a standard military tactic during the Warring States period; as the Yellow River valley was the major entryway to the Guanzhong area and the state of Qin from the North China Plain, Qin fortified the Hangu Pass. Major flooding in AD 11 is credited with the downfall of the short-lived Xin dynasty, another flood in AD 70 returned the river north of Shandong on its present course. From around the beginning of the 3rd century, the importance of the Hangu Pass was reduced, with the major fortifications a
The 21st century is the current century of the Anno Domini era or Common Era, in accordance with the Gregorian calendar. It began on January 1, 2001, will end on December 31, 2100, it is the first century of the 3rd millennium. It is distinct from the century known as the 2000s which began on January 1, 2000 and will end on December 31, 2099; the first years of the 21st century have thus far been marked by the rise of a global economy and Third World consumerism, mistrust in government, deepening global concern over terrorism and an increase in the power of private enterprise. The Arab Spring of the early 2010s led to mixed outcomes in the Arab world; the Third Industrial Revolution which began around the 1980s continues into the present, is expected to transition into Industry 4.0 and the Fourth Industrial Revolution by as early as 2030. Millennials and Generation Z come of rise to prominence in this century. In 2016, the United Kingdom decided causing Brexit. Advances in technology such as ultrasound, prenatal genetic testing and genetic engineering is changing the demographics and has the potential to change the genetic makeup of the human population.
Because of sex selective abortion, fewer girls have been born in the 21st century compared to in past centuries because of son preference in East and South Asia. In 2014 only 47 percent of Indian births were of girls; this has led to an increase in bachelors in countries such as India. The first genetically modified children were born in November 2018 in China, beginning a new biological era for the human species and raising great controversy. Anxiety and depression rates are rising in many other parts of the world. However, suicide rates have fallen in Europe and most of the rest of the world so far this century, declining 29% globally between 2000 and 2018, despite rising 18% in the United States in the same period; the decline in suicide has been most notable among Chinese and Indian women, the elderly and middle-aged Russian men. The entire written works of mankind, from the beginning of recorded history to 2003, in all known languages, is estimated to be at five exabytes of data. Since 2003, with the birth of social media and "user-generated content", the same amount of data is created every two days.
The advancement of the sum total of human knowledge and information continues to grow at an exponential rate. Telecommunications in the early 21st century are much more advanced and universal than they were in the late 20th century. Only a few percent of the world's population were Internet users and cellular phone owners in the late 1990s. In the 2010s, artificial intelligence in the form of deep learning and machine learning became more prevalent, is prominently used in Gmail and Google's search engine, as well as in banking, the military and other niches. In 2017, 14% of the world's population still lacked access to electricity. In 2001, Dennis Tito became the first space tourist. Entrepreneurs such as Elon Musk and Richard Branson are working towards commercial space exploration and tourism, China and India have made substantial strides in their space program. On January 3, 2019, China landed a robotic spacecraft on the far side of the Moon, being the first to do so. War and most kinds of crime and violence have declined compared to the 20th century.
Malnourishment and poverty are still widespread globally, but fewer people live in the most extreme forms of poverty, relative to recorded history. In 1990 one-in-four people were malnourished, nearly 36% of the world's population lived in extreme poverty. If current trends hold, the United Nations projects the eradication of famine and extreme poverty by the end of this century; the Facebook–Cambridge Analytica data scandal draws international attention to the possible negative effects of social media on influencing citizen's views in regards to the 2016 United States presidential election. The world population was about 6.1 billion at the start of the 21st century and reached 7.7 billion by January 2019. It is estimated to reach about 8.6 billion by the year 2030, 9.8 billion by the year 2050. According to the United Nations World Urbanization prospects, 60% of the world's human population are projected to live in megacities and megalopolises by 2030, 70% by 2050, 90% by 2080. By 2040, more than 5 times the current global gross domestic product are expected to be invested in urban infrastructure and its use.
Life expectancy is increasing. A baby born in 2016 can on average expect to live 72 years. Ten million Britons are expected to live to 100 or older; however climate change remains an serious concern. Economically and politically the United States and Western Europe were dominant at the beginning of the century. In terms of purchasing power parity India's economy became larger than that of Japan around the year 2011; the ongoing impact of technological unemployment due to automation and computerization on job employment is massive: the rat
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
China the People's Republic of China, is a country in East Asia and the world's most populous country, with a population of around 1.404 billion. Covering 9,600,000 square kilometers, it is the third- or fourth-largest country by total area. Governed by the Communist Party of China, the state exercises jurisdiction over 22 provinces, five autonomous regions, four direct-controlled municipalities, the special administrative regions of Hong Kong and Macau. China emerged as one of the world's earliest civilizations, in the fertile basin of the Yellow River in the North China Plain. For millennia, China's political system was based on hereditary monarchies, or dynasties, beginning with the semi-legendary Xia dynasty in 21st century BCE. Since China has expanded, re-unified numerous times. In the 3rd century BCE, the Qin established the first Chinese empire; the succeeding Han dynasty, which ruled from 206 BC until 220 AD, saw some of the most advanced technology at that time, including papermaking and the compass, along with agricultural and medical improvements.
The invention of gunpowder and movable type in the Tang dynasty and Northern Song completed the Four Great Inventions. Tang culture spread in Asia, as the new Silk Route brought traders to as far as Mesopotamia and Horn of Africa. Dynastic rule ended in 1912 with the Xinhai Revolution; the Chinese Civil War resulted in a division of territory in 1949, when the Communist Party of China established the People's Republic of China, a unitary one-party sovereign state on Mainland China, while the Kuomintang-led government retreated to the island of Taiwan. The political status of Taiwan remains disputed. Since the introduction of economic reforms in 1978, China's economy has been one of the world's fastest-growing with annual growth rates above 6 percent. According to the World Bank, China's GDP grew from $150 billion in 1978 to $12.24 trillion by 2017. Since 2010, China has been the world's second-largest economy by nominal GDP and since 2014, the largest economy in the world by purchasing power parity.
China is the world's largest exporter and second-largest importer of goods. China is a recognized nuclear weapons state and has the world's largest standing army and second-largest defense budget; the PRC is a permanent member of the United Nations Security Council as it replaced the ROC in 1971, as well as an active global partner of ASEAN Plus mechanism. China is a leading member of numerous formal and informal multilateral organizations, including the Shanghai Cooperation Organization, WTO, APEC, BRICS, the BCIM, the G20. In recent times, scholars have argued that it will soon be a world superpower, rivaling the United States; the word "China" has been used in English since the 16th century. It is not a word used by the Chinese themselves, it has been traced through Portuguese and Persian back to the Sanskrit word Cīna, used in ancient India."China" appears in Richard Eden's 1555 translation of the 1516 journal of the Portuguese explorer Duarte Barbosa. Barbosa's usage was derived from Persian Chīn, in turn derived from Sanskrit Cīna.
Cīna was first used including the Mahābhārata and the Laws of Manu. In 1655, Martino Martini suggested that the word China is derived from the name of the Qin dynasty. Although this derivation is still given in various sources, it is complicated by the fact that the Sanskrit word appears in pre-Qin literature; the word may have referred to a state such as Yelang. The meaning transferred to China as a whole; the origin of the Sanskrit word is still a matter of debate, according to the Oxford English Dictionary. The official name of the modern state is the "People's Republic of China"; the shorter form is "China" Zhōngguó, from zhōng and guó, a term which developed under the Western Zhou dynasty in reference to its royal demesne. It was applied to the area around Luoyi during the Eastern Zhou and to China's Central Plain before being used as an occasional synonym for the state under the Qing, it was used as a cultural concept to distinguish the Huaxia people from perceived "barbarians". The name Zhongguo is translated as "Middle Kingdom" in English.
Archaeological evidence suggests that early hominids inhabited China between 2.24 million and 250,000 years ago. The hominid fossils of Peking Man, a Homo erectus who used fire, were discovered in a cave at Zhoukoudian near Beijing; the fossilized teeth of Homo sapiens have been discovered in Fuyan Cave in Hunan. Chinese proto-writing existed in Jiahu around 7000 BCE, Damaidi around 6000 BCE, Dadiwan from 5800–5400 BCE, Banpo dating from the 5th millennium BCE; some scholars have suggested. According to Chinese tradition, the first dynasty was the Xia, which emerged around 2100 BCE; the dynasty was considered mythical by historians until scientific excavations found early Bronze Age sites at Erlitou, Henan in 1959. It remains unclear whether these sites are the remains of the Xia dynasty or of another culture from the same period; the succeeding Shang dynasty is the earliest to be confirmed by contemporary records. The Shang ruled the plain of the Yellow River in eastern China from the 17th to the 11th century BCE.
Their oracle bone script
Democratic Republic of the Congo
The Democratic Republic of the Congo known as DR Congo, the DRC, DROC, Congo-Kinshasa, or the Congo, is a country located in Central Africa. It is sometimes anachronistically referred to by its former name of Zaire, its official name between 1971 and 1997, it is, by area, the largest country in Sub-Saharan Africa, the second-largest in all of Africa, the 11th-largest in the world. With a population of over 78 million, the Democratic Republic of the Congo is the most populated Francophone country, the fourth-most-populated country in Africa, the 16th-most-populated country in the world. Eastern DR Congo is the scene of ongoing military conflict in Kivu, since 2015. Centred on the Congo Basin, the territory of the DRC was first inhabited by Central African foragers around 90,000 years ago and was reached by the Bantu expansion about 3,000 years ago. In the west, the Kingdom of Kongo ruled around the mouth of the Congo River from the 14th to 19th centuries. In the centre and east, the kingdoms of Luba and Lunda ruled from the 16th and 17th centuries to the 19th century.
In the 1870s, just before the onset of the Scramble for Africa, European exploration of the Congo Basin was carried out, first led by Henry Morton Stanley under the sponsorship of Leopold II of Belgium. Leopold formally acquired rights to the Congo territory at the Berlin Conference in 1885 and made the land his private property, naming it the Congo Free State. During the Free State, the colonial military unit, the Force Publique, forced the local population to produce rubber, from 1885 to 1908, millions of Congolese died as a consequence of disease and exploitation. In 1908, despite initial reluctance, formally annexed the Free State, which became the Belgian Congo; the Belgian Congo achieved independence on 30 June 1960 under the name Republic of the Congo. Congolese nationalist Patrice Lumumba was elected the first Prime Minister, while Joseph Kasa-Vubu became the first President. Conflict arose over the administration of the territory; the provinces of Katanga, under Moïse Tshombe, South Kasai attempted to secede.
After Lumumba turned to the Soviet Union for assistance in the crisis, the U. S. and Belgium became wary and oversaw his removal from office by Kasa-Vubu on 5 September and ultimate execution by Belgian-led Katangese troops on 17 January 1961. On 25 November 1965, Army Chief of Staff Joseph-Désiré Mobutu, who renamed himself Mobutu Sese Seko came into power through a coup d'état. In 1971, he renamed the country Zaire; the country was run as a dictatorial one-party state, with his Popular Movement of the Revolution as the sole legal party. Mobutu's government received considerable support from the United States, due to its anti-communist stance during the Cold War. By the early 1990s, Mobutu's government began to weaken. Destabilisation in the east resulting from the 1994 Rwandan genocide and disenfranchisement among the eastern Banyamulenge population led to a 1996 invasion led by Tutsi FPR-ruled Rwanda, which began the First Congo War. On 17 May 1997, Laurent-Désiré Kabila, a leader of Tutsi forces from the province of South Kivu, became President after Mobutu fled to Morocco, reverting the country's name to the Democratic Republic of the Congo.
Tensions between President Kabila and the Rwandan and Tutsi presence in the country led to the Second Congo War from 1998 to 2003. Nine African countries and around twenty armed groups became involved in the war, which resulted in the deaths of 5.4 million people. The two wars devastated the country. President Laurent-Désiré Kabila was assassinated by one of his bodyguards on 16 January 2001 and was succeeded eight days as President by his son Joseph; the Democratic Republic of the Congo is rich in natural resources but has had political instability, a lack of infrastructure, issues with corruption and centuries of both commercial and colonial extraction and exploitation with little holistic development. Besides the capital Kinshasa, the two next largest cities Lubumbashi and Mbuji-Mayi are both mining communities. DR Congo's largest export is raw minerals, with China accepting over 50% of DRC's exports in 2012. In 2016, DR Congo's level of human development was ranked 176th out of 187 countries by the Human Development Index.
As of 2018, around 600,000 Congolese have fled to neighbouring countries from conflicts in the centre and east of the DRC. Two million children risk starvation, the fighting has displaced 4.5 million people. The sovereign state is a member of the United Nations, Non-Aligned Movement, African Union, COMESA; the Democratic Republic of the Congo is named after the Congo River, which flows throughout the country. The Congo River is the world's second largest river by discharge; the Comité d'études du haut Congo, established by King Leopold II of Belgium in 1876, the International Association of the Congo, established by him in 1879, were named after the river. The Congo River itself was named by early European sailors after the Kingdom of Kongo and its Bantu inhabitants, the Kongo people, when they encountered them in the 16th century; the word Kongo comes from the Kongo language. According to American writer Samuel Henry Nelson "It is probable that the word'Kongo' itself implies a public gathering and that it is based on the root konga,'to gather'."
The modern name of the Kongo people, Bakongo was introduced in the early 20th century. The Democratic Republic of the Congo has been known in the past as, in chronological order, the Congo Free State, Belgian Congo, the Repub
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