Golkonda known as Golconda, Gol konda, or Golla konda, is a citadel and fort in Southern India and was the capital of the medieval sultanate of the Qutb Shahi dynasty, is situated 11 km west of Hyderabad. It is a tehsil of Hyderabad district, India; the region is known for the mines that have produced some of the world's most famous gems, including the Koh-i-Noor, the Hope Diamond, Nassak Diamond and the Noor-ul-Ain. Golkonda was known as Mankal. Golkonda Fort was first built by the Kakatiyas as part of their western defenses along the lines of the Kondapalli Fort; the city and the fortress were built on a granite hill, 120 meters high, surrounded by massive battlements. The fort was strengthened by Rani Rudrama Devi and her successor Prataparudra; the fort came under the control of the Musunuri Nayaks, who defeated the Tughlaqi army occupying Warangal. It was ceded by the Musunuri Kapaya Bhupathi to the Bahmani Sultanate as part of a treaty in 1364. Under the Bahmani Sultanate, Golkonda rose to prominence.
Sultan Quli Qutb-ul-Mulk, sent as a governor of Telangana, established it as the seat of his government around 1501. Bahmani rule weakened during this period, Sultan Quli formally became independent in 1538, establishing the Qutb Shahi dynasty based in Golkonda. Over a period of 62 years, the mud fort was expanded by the first three Qutb Shahi sultans into the present structure, a massive fortification of granite extending around 5 km in circumference, it remained the capital of the Qutb Shahi dynasty until 1590 when the capital was shifted to Hyderabad. The Qutb Shahis expanded the fort; the fort fell into ruin in 1687, after an eight-month-long siege led to its fall at the hands of the Mughal emperor Aurangzeb. The Golkonda Fort used to have a vault where the famous Koh-i-Noor and Hope diamonds were once stored along with other diamonds. Golkonda is renowned for the diamonds found on the south-east at Kollur Mine near Kollur, Guntur district and Atkur in Krishna district and cut in the city during the Kakatiya reign.
At that time, India had the only known diamond mines in the world. Golkonda's mines yielded many diamonds. Golkonda was the market city of the diamond trade, gems sold there came from a number of mines; the fortress-city within the walls was famous for diamond trade. However, Europeans believed. Magnificent diamonds were taken from the mines in the region surrounding Golkonda, including the Daria-i-Noor or "Sea of Light", at 185 carats, the largest and finest diamond of the crown jewels of Iran, its name has come to be associated with great wealth. Gemologists use this classification to denote a diamond with a complete lack of nitrogen. Many famed diamonds are believed to have been excavated from the mines of Golkonda, such as: Daria-i-Noor Noor-ul-Ain Koh-i-Noor Hope Diamond Princie Diamond Regent Diamond Wittelsbach-Graff Diamond By the 1880s, "Golkonda" was being used generically by English speakers to refer to any rich mine, to any source of great wealth. During the Renaissance and the early modern eras, the name "Golkonda" acquired a legendary aura and became synonymous for vast wealth.
The mines brought riches to the Qutb Shahis of Hyderabad State, who ruled Golkonda up to 1687 to the Nizam of Hyderabad, who ruled after the independence from the Mughal Empire in 1724 until 1948, when the Indian integration of Hyderabad occurred. The Golkonda fort is listed as an archaeological treasure on the official "List of Monuments" prepared by the Archaeological Survey of India under The Ancient Monuments and Archaeological Sites and Remains Act. Golkonda consists of four distinct forts with a 10 km long outer wall with 87 semicircular bastions, eight gateways, four drawbridges, with a number of royal apartments and halls, mosques, stables, etc. inside. The lowest of these is the outermost enclosure into which we enter by the "Fateh Darwaza" studded with giant iron spikes near the south-eastern corner. An acoustic effect can be experienced at Fateh Darwazaan, characteristic of the engineering marvels at Golkonda. A hand clap at a certain point below the dome at the entrance reverberates and can be heard at the'Bala Hisar' pavilion, the highest point a kilometer away.
This worked. The whole of the Golkonda Fort complex and its surrounding spreads across 11 km of total area and discovering its every nook is an arduous task. A visit to the fort reveals the architectural beauty in many of the pavilions, gates and domes. Divided into four district forts, the architectural valour still gleams in each of the apartments, temples and stables; the graceful gardens of the fort may have lost their fragrance, for which they were known 400 years ago, yet a walk in these former gardens should be in your schedule when exploring the past glories of Golkonda Fort. Bala Hissar Gate is the main entrance to the fort located on the eastern side, it has a pointed arch bordered by rows of scroll work. The spandrels have yalis and decorated roundels; the area above the door has peacocks with ornate tails flanking an ornamental arched niche. The granite block lintel below has sculpted yalis flanking a disc; the design of peacocks and lions is t
A tiara is a jeweled, ornamental crown traditionally worn by women. It is worn during formal occasions if the dress code is white tie. Today, the word "tiara" is used interchangeably with the word "diadem", tiara is translated to a word similar to diadem in other languages. Both words come from head ornaments worn by ancient women to denote high status; as Geoffrey Munn notes, "The word'tiara' is Persian in origin—the name first denoted the high-peaked head-dresses of Persian kings, which were encircled by'diadems'. Now, it is used to describe every form of decorative head ornament." Ancient Greeks and Romans used gold to make wreath-shaped head ornaments, while the Scythians' resembled a stiff halo that would serve as the inspiration for Russian kokoshniks. The use of tiaras and diadems declined along with the decline of the Roman Empire and the rise of Christianity. In the late 18th century, Neoclassicism gave rise to a revival of tiaras, but this time it was a female adornment. Jewelers taking inspiration from Ancient Greece and Rome created new wreaths made from precious gemstones.
Napoleon and his wife Joséphine de Beauharnais are credited with popularizing tiaras along with the new Empire style. Napoleon wanted the French court to be the grandest in Europe and had given his wife many fabulous parures which included tiaras. Queen Elizabeth II is said to have the largest and most valuable collection of tiaras in the world, many of which are heirlooms of the British royal family, she is seen wearing them on state occasions. The Queen inherited many of them from Queen Alexandra. Queen Mary purchased the Grand Duchess Vladimir tiara in the 1920s, it consists of numerous interlocking diamond circles. Pearl drops can be attached inside the emeralds. Queen Mary had a tiara made for the Delhi Durbar held in 1911 in India, it is now on loan for wearing by wife of Charles, Prince of Wales. Queen Elizabeth II commissioned a diamond tiara. A gift of aquamarines she received as a present from the people of Brazil were added to diamonds to make a new tiara. Other queens and princesses wear tiaras at formal evening occasions.
The Swedish Royal Family have a magnificent collection as do the Danish, the Dutch, Spanish monarchies. Many of the Danish royal jewels came into the collection when Princess Louise of Sweden married the future King Frederick VIII of Denmark; the Romanov dynasty had a superb collection up until the revolution of 1917. The Iranian royal family had a large collection of tiaras. Since the Iranian Revolution, they are housed at the National Jewelry Museum in Tehran. Although associated with women of reigning and noble families, tiaras have been worn by commoners as well rich American socialites like Barbara Hutton. Tiaras are a semi-circular or circular band of precious metal, decorated with jewels and are worn as a form of adornment. Tiaras are worn by women around their head or on the forehead as a circlet on formal or high social occasions. Tiaras are used to "crown" the winners of beauty pageants. During the Victorian Age in the United States, tiaras were being seen on non-royal ladies of means.
“In Paris great aigrette balls were organized by aristocrate families who were proud of their name and their past, such as Dutcesse de Gramount with her ‘Crinoline Ball’ and Princess Jacques de Broglie with her ‘Gemstone Ball’ of 1914. In distant New York, Philadelphia an Newport on the other hand, Mrs. William Astor, Mrs. George J. Gould, Mrs. W. K. Vanderbilt and Eva Stotesbury entertained with a degree of magnificence which made European balls appear insignificant; the moneyed classes of the United States, who had raised themselves above their bourgeois origins through their own hard work, set out to rival the historical aristocracy of Europe. In friendly competition with her rivals, the well-to-do American women refused to forgo any of the attributes sanctioned by society; these accessories included country houses imported from Europe complete with ancestral portraits and furnishings, as well as tiaras order from Cartier’s in Paris and New York.” – Cartier By Hans Nadelhoffer By the 1920s, the tiara and similar tiara headbands became popular in the United States.
They were worn not only with formal ballroom gowns, but became popular with the flappers and their parties. Tiaras made of plastic, Swarovski crystals, or any other non-precious material are considered costume jewelry, they are worn by women on special occasions such as homecoming or prom and at their quinceañera or wedding. They are worn by the winners of beauty pageants and girls dressing up as Disney princesses. Tiaras are worn by actresses in film and television. In 2013, Cartier created a replica of the ruby and diamond tiara they had made in 1956 for Princess Grace of Monaco for the film, Grace of Monaco starring Nicole Kidman. Aigrette Circlet Coronet Diadem Headband Military tiara Papal tiara Elizabeth II's jewels The Royal Collection tiaras of Queen Elizabeth II New York Times - Are Tiaras the New Power Scrunchies? Maclean's - Rocking the Tiara Wall Street Journal - Fit for a Queen
Harry Winston was an American jeweler. He donated the Hope Diamond to the Smithsonian Institution in 1958 after owning it for a decade, he traded the Portuguese Diamond to the Smithsonian in 1963. Winston founded the Harry Winston Inc. in New York City in 1932. He had been called by many as the "King of Diamonds". Winston's father Jacob started a small jewelry business after he and his mother immigrated to the United States from Ukraine. While growing up, he worked in his father's shop; when he was twelve years old, he recognized a two-carat emerald in a pawn shop, bought it for 25 cents, sold it two days for $800. Winston started his business in 1920 and opened his first store in New York City in 1932. Winston's jewelry empire began in 1926, with his acquisition of Arabella Huntington's jewelry collection, for $1.2 million. The wife of railroad magnate Henry E. Huntington, Arabella amassed one of the world's most prestigious collections of jewelry from Parisian jewelers such as Cartier; when Winston bought the collection after her death, the designs of the jewelry in the collection were quite old fashioned.
Winston redesigned the jewelry into more contemporary styles and showcased his unique skill at jewelry crafting. According to the Huntington museum, "He boasted that Arabella's famous necklace of pearls now adorned the necks of at least two dozen women around the world."When he died, Winston left the company to his two sons and Bruce, who entered into a decade-long battle over the control of the company. In 2000, Ronald along with new business partner, Fenway Partners, bought Bruce out from the company for $54.1 million. Winston was among the most noted jewelers in the world, well-known to the general public. In the 1953 musical film Gentlemen Prefer Blondes, the song "Diamonds Are a Girl's Best Friend" includes the spoken interjection "Talk to me, Harry Winston, tell me all about it!" The Lauren Weisberger comic novel, Chasing Harry Winston, was published in May 2008. In 2015, Harry Winston, Inc. operated 39 salons and numerous retail affiliates in locations such as New York, Beverly Hills, Las Vegas, Honolulu, Bal Harbour, Costa Mesa, other countries around the world.
Reference: The Arcots, first 33.70 and 23.65 carats, recut by Winston to 31.01 and 18.85 carats, respectively. The stones were thought to be a match, but when Winston bought them, removed them from their settings and discovered they were not, he decided to recut them to improve their clarity and brilliance. Both were either colorless or near-colorless, antique pear-shaped brilliants; the Anastasia, three emerald cuts weighing 42.95, 30.90 and 22.88 carats, all D color and Flawless clarity. Cut from a rough crystal weighing 307.30 carats Winston had purchased in 1972, largest gem named after Anastasia Nikolaevna, daughter of Czar Nicholas II. The Ashoka a 42.47 carats, modified elongated cushion brilliant. Purchased by Winston from a Chinese dealer in 1947. Stone was recut in 1977 from its original weight of 42.47 carats before it was sold again as a ring. The Blue Heart, a 30.82 carats, heart-shaped brilliant. After the cut was made, Cartier sold it to the Unzue family of Argentina in 1910, it reappeared in Paris in 1953 where it was purchased by an important European titled family purchased by Harry Winston in 1959.
Winston mounted it in a ring and sold it to Marjorie Merriweather Post, who donated it to the Smithsonian Institution. The Briolette of India, a 90.38 carats, briolette cut. The Cornflower Blue, 31.93 carats pear brilliant. The larger stone was sold in 1969 as the pendant for a diamond necklace. Winston repurchased it two years then sold it to a Middle Eastern client; the round brilliant was set as a ring and sold in 1969. In 1987 the pear brilliant was auctioned in Switzerland; the Countess Széchényi, a 62.05 carats, D color, pear-shaped brilliant. Purchased by Winston in 1959 from namesake and recut to a flawless 59.38 carats. Sold to an American industrialist in 1966; the Crown of Charlemagne, a 37.05 carats, sky blue, Old European cut brilliant. The Deal Sweetener, a 45.31 carats diamond plus four smaller stones, D color and Flawless, emerald cut. In 1974 Winston bought a large parcel of diamonds worth $24,500,000—at that time the largest individual sale of diamonds in history. Harry Oppenheimer, head of De Beers Consolidated Mines Ltd. arranged the transaction.
When Winston asked Oppenheimer, "How about a little something to sweeten the deal?" Harry Oppenheimer pulled a 181 carats rough diamond out of his pocket and rolled it across the table. Winston picked up the stone and said "Thanks." It was cut into the largest being named the Deal Sweetener. Other gems cut from the crystal: An emerald cut of 24.67 carats, plus three pear shapes of 10.80, 4.19 and 1.45 carats, respectively. All were sold that same year; the Deepdene, a 104.52 carats, antique cushion brilliant. Purchased by Winston in 1954 from Cary W. Bok sold the following year to Mrs. Eleanor Loder of Canada. Resurfaced in 1971 and put up for auction at Christie's in
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
Noor ul Ain
Noor ul Ain is a Pakistani romantic drama serial started airing on ARY Digital from 10 February 2018. It is directed by Sarmad Khoosat, it stars Imran Abbas and Sajal Aly in the leading roles. The drama was first aired 10 February on ARY Digital on every Saturday moved to Tuesday time slot at 9:00 P. M. Despite the strong Cast, Production house and Promotions, the drama turned out to be a major critical and commercial Disaster. Story of Noor ul Ain and Khizer that how their first accidental meet change their lives and how they fall in love for one together. Sajal Ali as Noor ul Ain Imran Abbas as Khizar Hayat Iffat Rahim as Ghazala Marina Khan Irfan Khoosat as Qasim Maryam Noor as Sofiya "Sofi" Ammad Mir as Nauman Music is composed by Saad Sultan and OST is sung by acclaimed singers Zeb Bangash and Ali Sethi. According to Gulf News, Zeb Bangash got an old melody project for this OST Official website
Mohammad Reza Pahlavi
Mohammad Reza Pahlavi known as Mohammad Reza Shah, was the last Shah of Iran from 16 September 1941 until his overthrow by the Islamic Revolution on 11 February 1979. A close ally of the United States, he tried to use vast oil revenues to generate a rapid industrial and military modernisation, as well as economic and social reforms. In reaction religious forces overthrew him. Mohammad Reza came to power during World War II after an Anglo-Soviet invasion forced the abdication of his father, Reza Shah Pahlavi. During Mohammad Reza's reign, the British owned oil industry was nationalised, under Prime Minister Mohammad Mosaddegh, until a UK and US -backed coup d'état deposed Mosaddegh and brought back foreign oil firms under the Consortium Agreement of 1954. Under Mohammad Reza's reign, Iran marked the anniversary of 2,500 years of continuous Persian monarchy since the founding of the Achaemenid Empire by Cyrus the Great – concurrent with this celebration, Mohammad Reza changed the benchmark of the Iranian calendar from the hegira to the beginning of the First Persian Empire, measured from Cyrus the Great's coronation.
Mohammad Reza introduced the White Revolution, a series of economic and political reforms with the proclaimed intention of transforming Iran into a global power and modernising the nation by nationalising certain industries and granting women suffrage. Mohammad Reza lost support from the Shi'a clergy of Iran as well as the working class due to his strong policy of modernisation, laïcité, conflict with the traditional class of wealthy merchants known as bazaaris, relations with Israel, corruption issues surrounding himself and the royal family, the ruling elite. Various additional controversial policies were enacted, including the banning of the Communism and Marxism-leninism including the Tudeh Party and a general suppression of political dissent by Iran's intelligence agency, SAVAK. According to official statistics, Iran had as many as 2,200 political prisoners in 1978, a number which multiplied as a result of the revolution. Several other factors contributed to strong opposition to the Shah amongst certain groups within Iran, the most significant of which were US and UK support for his regime, clashes with leftists and Islamists.
By 1979, political unrest had transformed into a revolution which, on 17 January, forced him to leave Iran. Soon thereafter, the Iranian monarchy was formally abolished, Iran was declared an Islamic republic led by Ruhollah Khomeini. Facing execution should he return to Iran, he died in exile in Egypt, whose president, Anwar Sadat, had granted him asylum. Due to his status as the last Shah of Iran, he is known as "The Shah". Born in Tehran, to Reza Khan and his second wife, Tadj ol-Molouk, Mohammad Reza was the eldest son of Reza Khan, who became the first Shah of the Pahlavi dynasty, the third of his eleven children, his father, a former Brigadier-General of the Persian Cossack Brigade, was of Mazandarani and Georgian origin. His father was born in Savadkuh County, Māzandarān Province. Mohammad Reza's paternal grandmother, Noush-Afarin, was a Muslim immigrant from Georgia, whose family had emigrated to mainland Iran after Iran was forced to cede all of its territories in the Caucasus following the Russo-Persian Wars several decades prior to Reza Khan's birth.
Mohammad Reza's mother, Tadj ol-Molouk, was of Azerbaijani origin, being born in Baku, Russian Empire. Mohammad Reza was born along with Ashraf. However, Mohammad Reza, Ali Reza, their older half-sister, were not royalty by birth, as their father did not become Shah until 1925. Reza Khan was always convinced that his sudden quirk of good fortune had commenced in 1919 with the birth of his son, dubbed khoshghadam. Like most Iranians at the time, Reza Khan did not have a surname and after the 1921 Persian coup d'état which deposed Ahmad Shah Qajar, he was informed that he would need a name for his house; this led Reza Khan to pass a law ordering all Iranians to take a surname. At his father's coronation on 24 April 1926, Mohammad Reza was proclaimed Crown Prince. Mohammad Reza described his father in his book Mission for My Country as "one of the most frightening men" he had known, depicting Reza Khan as a dominating man with a violent temper. A tough and ambitious soldier who became the first Persian to command the elite Russian-trained Cossack Brigade, Reza Khan liked to kick subordinates in the groin who failed to follow his orders.
Reza Khan believed if fathers showed love for their sons, it caused homosexuality in life, to ensure his favourite son was heterosexual, denied him any love and affection when he was young, though he become more affectionate towards the Crown Prince when he was a teenager. Reza Khan always addressed his son as shoma and refused to use more informal tow, in turn was addressed by his son using the same word; the Polish journalist Ryszard Kapuściński observed in his book Shah of Shahs that looking at old photographs of Reza Khan and his son, he was struck by how self-confident and assured Reza Khan appeared in his uniform while Mohammad Reza appeared nervous and jittery in his uniform standing next to his father. In the 1930s, Reza Khan
Platinum is a chemical element with symbol Pt and atomic number 78. It is a dense, ductile unreactive, silverish-white transition metal, its name is derived from the Spanish term platino, meaning "little silver". Platinum is a member of the platinum group of elements and group 10 of the periodic table of elements, it has six occurring isotopes. It is one of the rarer elements in Earth's crust, with an average abundance of 5 μg/kg, it occurs in some nickel and copper ores along with some native deposits in South Africa, which accounts for 80% of the world production. Because of its scarcity in Earth's crust, only a few hundred tonnes are produced annually, given its important uses, it is valuable and is a major precious metal commodity. Platinum is one of the least reactive metals, it has remarkable resistance to corrosion at high temperatures, is therefore considered a noble metal. Platinum is found chemically uncombined as native platinum; because it occurs in the alluvial sands of various rivers, it was first used by pre-Columbian South American natives to produce artifacts.
It was referenced in European writings as early as 16th century, but it was not until Antonio de Ulloa published a report on a new metal of Colombian origin in 1748 that it began to be investigated by scientists. Platinum is used in catalytic converters, laboratory equipment, electrical contacts and electrodes, platinum resistance thermometers, dentistry equipment, jewelry. Being a heavy metal, it leads to health problems upon exposure to its salts. Compounds containing platinum, such as cisplatin and carboplatin, are applied in chemotherapy against certain types of cancer; as of 2018, the value of platinum is $833.00 per ounce. Pure platinum is a lustrous and malleable, silver-white metal. Platinum is more ductile than gold, silver or copper, thus being the most ductile of pure metals, but it is less malleable than gold; the metal has excellent resistance to corrosion, is stable at high temperatures and has stable electrical properties. Platinum does oxidize, forming PtO2, at 500 °C, it reacts vigorously with fluorine at 500 °C to form platinum tetrafluoride.
It is attacked by chlorine, bromine and sulfur. Platinum is insoluble in hydrochloric and nitric acid, but dissolves in hot aqua regia, to form chloroplatinic acid, H2PtCl6, its physical characteristics and chemical stability make it useful for industrial applications. Its resistance to wear and tarnish is well suited to use in fine jewellery; the most common oxidation states of platinum are +2 and +4. The +1 and +3 oxidation states are less common, are stabilized by metal bonding in bimetallic species; as is expected, tetracoordinate platinum compounds tend to adopt 16-electron square planar geometries. Although elemental platinum is unreactive, it dissolves in hot aqua regia to give aqueous chloroplatinic acid: Pt + 4 HNO3 + 6 HCl → H2PtCl6 + 4 NO2 + 4 H2OAs a soft acid, platinum has a great affinity for sulfur, such as on dimethyl sulfoxide. In 2007, Gerhard Ertl won the Nobel Prize in Chemistry for determining the detailed molecular mechanisms of the catalytic oxidation of carbon monoxide over platinum.
Platinum has six occurring isotopes: 190Pt, 192Pt, 194Pt, 195Pt, 196Pt, 198Pt. The most abundant of these is 195 Pt, it is the only stable isotope with a non-zero spin. 190Pt is the least abundant at only 0.01%. Of the occurring isotopes, only 190Pt is unstable, though it decays with a half-life of 6.5×1011 years, causing an activity of 15 Bq/kg of natural platinum. 198 Pt can undergo alpha decay. Platinum has 31 synthetic isotopes ranging in atomic mass from 166 to 204, making the total number of known isotopes 39; the least stable of these is 166Pt, with a half-life of 300 µs, whereas the most stable is 193Pt with a half-life of 50 years. Most platinum isotopes decay by some combination of beta alpha decay. 188Pt, 191Pt, 193Pt decay by electron capture. 190Pt and 198Pt are predicted to have energetically favorable double beta decay paths. Platinum is an rare metal, occurring at a concentration of only 0.005 ppm in Earth's crust. It is sometimes mistaken for silver. Platinum is found chemically uncombined as native platinum and as alloy with the other platinum-group metals and iron mostly.
Most the native platinum is found in secondary deposits in alluvial deposits. The alluvial deposits used by pre-Columbian people in the Chocó Department, Colombia are still a source for platinum-group metals. Another large alluvial deposit is in the Ural Mountains, it is still mined. In nickel and copper deposits, platinum-group metals occur as sulfides, tellurides and arsenides, as end alloys with nickel or copper. Platinum arsenide, sperrylite, is a major source of platinum associated with nickel ores in the Sudbury Basin deposit in Ontario, Canada. At Platinum, about 17,000 kg was mined between 1927 and 1975; the mine ceased operations in 1990. The rare sulfide minera