|
Toning (coin)
Toning on a coin is the change of colour brought about through oxidization, which forms a thin layer of tarnish on the metal's surface. Coin toning can vary in aesthetics, and thus can alternately add or detract from a coin's value. Coins with unusual toning colours or patterns tend to be valued by coin collectors. Toning is most common on silver coins, but can be found on coins minted from other metals and alloys, including gold, copper and cupronickel. Types of toning Different colors and patterns of toning can have varying effects on a coin's grade and value. For example, brown spotty toning could decrease a coin's value, while colorful rainbow toning could increase it. Similarly, toning can raise or lower a coin's grade by several points, as grading is based on factors including eye appeal and not just wear. Depending on the environment in which the toning took place, toned coins can come in many different colors and color combinations. Toning patterns may cover an entire co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1899 Reverse
Events January 1899 * January 1 ** Spanish rule ends in Cuba, concluding 400 years of the Spanish Empire in the Americas. ** Queens and Staten Island become administratively part of New York City. * January 2 – **Bolivia sets up a customs office in Puerto Alonso, leading to the Brazilian settlers there to declare the Republic of Acre in a revolt against Bolivian authorities. **The first part of the Jakarta Kota–Anyer Kidul railway on the island of Java is opened between Batavia Zuid ( Jakarta Kota) and Tangerang. * January 3 – Hungarian Prime Minister Dezső Bánffy fights an inconclusive duel with his bitter enemy in parliament, Horánszky Nándor. * January 4 – **U.S. President William McKinley's declaration of December 21, 1898, proclaiming a policy of benevolent assimilation of the Philippines as a United States territory, is announced in Manila by the U.S. commander, General Elwell Otis, and angers independence activists who had fought against Spa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coin
A coin is a small, flat (usually depending on the country or value), round piece of metal or plastic used primarily as a medium of exchange or legal tender. They are standardized in weight, and produced in large quantities at a mint in order to facilitate trade. They are most often issued by a government. Coins often have images, numerals, or text on them. ''Obverse'' and its opposite, ''reverse'', refer to the two flat faces of coins and medals. In this usage, ''obverse'' means the front face of the object and ''reverse'' means the back face. The obverse of a coin is commonly called ''heads'', because it often depicts the head of a prominent person, and the reverse ''tails''. Coins are usually made of metal or an alloy, or sometimes of man-made materials. They are usually disc shaped. Coins, made of valuable metal, are stored in large quantities as bullion coins. Other coins are used as money in everyday transactions, circulating alongside banknotes. Usually the hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Redox
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate (chemistry), substrate change. Oxidation is the loss of Electron, electrons or an increase in the oxidation state, while reduction is the gain of electrons or a decrease in the oxidation state. There are two classes of redox reactions: * ''Electron-transfer'' – Only one (usually) electron flows from the reducing agent to the oxidant. This type of redox reaction is often discussed in terms of redox couples and electrode potentials. * ''Atom transfer'' – An atom transfers from one substrate to another. For example, in the rusting of iron, the oxidation state of iron atoms increases as the iron converts to an oxide, and simultaneously the oxidation state of oxygen decreases as it accepts electrons released by the iron. Although oxidation reactions are commonly associated with the formation of oxides, other chemical species can serve the same function. In hydrogen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tarnish
Tarnish is a thin layer of corrosion that forms over copper, brass, aluminum, magnesium, neodymium and other similar metals as their outermost layer undergoes a chemical reaction. Tarnish does not always result from the sole effects of oxygen in the air. For example, silver needs hydrogen sulfide to tarnish, although it may tarnish with oxygen over time. It often appears as a dull, gray or black film or coating over metal. Tarnish is a surface phenomenon that is self-limiting, unlike rust. Only the top few layers of the metal react, and the layer of tarnish seals protects the underlying layers from reacting. Tarnish actually preserves the underlying metal in outdoor use, and in this form is called patina. The formation of patina is necessary in applications such as copper roofing, and outdoor copper, bronze, and brass statues and fittings. Patina is the name given to tarnish on copper-based metals, while toning is a term for the type of tarnish which forms on coins. Chemist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aesthetics
Aesthetics, or esthetics, is a branch of philosophy Philosophy (from , ) is the systematized study of general and fundamental questions, such as those about existence, reason, Epistemology, knowledge, Ethics, values, Philosophy of mind, mind, and Philosophy of language, language. Such quest ... that deals with the nature of beauty and taste (sociology), taste, as well as the philosophy of art (its own area of philosophy that comes out of aesthetics). It examines aesthetic values, often expressed through judgments of taste. Aesthetics covers both natural and artificial sources of experiences and how we form a judgment about those sources. It considers what happens in our minds when we engage with objects or environments such as viewing visual art, listening to music, reading poetry, experiencing a play, watching a fashion show, movie, sports or even exploring various aspects of nature. The philosophy of art specifically studies how artists imagine, create, and perfor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Numismatics
Numismatics is the study or collection of currency, including coins, tokens, paper money, medals and related objects. Specialists, known as numismatists, are often characterized as students or collectors of coins, but the discipline also includes the broader study of money and other means of payment used to resolve debts and exchange goods. The earliest forms of money used by people are categorised by collectors as "Odd and Curious", but the use of other goods in barter exchange is excluded, even where used as a circulating currency (e.g., cigarettes or instant noodles in prison). As an example, the Kyrgyz people used horses as the principal currency unit, and gave small change in lambskins; the lambskins may be suitable for numismatic study, but the horses are not. Many objects have been used for centuries, such as cowry shells, precious metals, cocoa beans, large stones, and gems. Etymology First attested in English 1829, the word ''numismatics'' comes from the adje ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cupronickel
Cupronickel or copper-nickel (CuNi) is an alloy of copper that contains nickel and strengthening elements, such as iron and manganese. The copper content typically varies from 60 to 90 percent. ( Monel is a nickel-copper alloy that contains a minimum of 52 percent nickel.) Despite its high copper content, cupronickel is silver in colour. Cupronickel is highly resistant to corrosion by salt water, and is therefore used for piping, heat exchangers and condensers in seawater systems, as well as for marine hardware. It is sometimes used for the propellers, propeller shafts, and hulls of high-quality boats. Other uses include military equipment and chemical, petrochemical, and electrical industries. Another common 20th-century use of cupronickel was silver-coloured coins. For this use, the typical alloy has 3:1 copper to nickel ratio, with very small amounts of manganese. In the past, true silver coins were debased with cupronickel, such as coins of the pound sterling from 1947 onw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coin Grading
Coin grading is the process of determining the grade or condition of a coin, one of the key factors in determining its value. A coin's grade is generally determined by six criteria: strike, preservation, luster, color, attractiveness, and occasionally the country/state in which they’re minted. Several grading systems have been developed. Certification services professionally grade coins for tiered fees. Overview A "grade" measures a coin's appearance. There are generally five main components which determine a coin's grade: strike, surface preservation, luster, coloration and eye appeal. Grading is subjective and even experts can disagree about the grade of a given coin. History U.S. coin grading has evolved over the years to a system of finer and finer grade distinctions. Originally, there were only two grades, new and used. This changed to the letter grading system beginning with the lowest grade – ''Basal State'' (also ''Poor'' (PO)), then continuing ''Fair'' (Fr), ''Abou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Morgan Dollar
The Morgan dollar is a United States dollar coin minted from 1878 to 1904, in 1921, and beginning again in 2021. It was the first standard silver dollar minted since the passage of the Coinage Act of 1873, which ended the free coining of silver and the production of the previous design, the Seated Liberty dollar. It contained 412.5 grains of 90% pure silver (or 371.25 gr = 24.056 g = 0.7735 oz t of pure silver). The coin is named after its designer, United States Mint Assistant Engraver George T. Morgan. The obverse depicts a profile portrait representing Liberty, modeled by Anna Willess Williams, while the reverse depicts an eagle with wings outstretched. The mint mark, if present, appears on the reverse above between D and O in "Dollar". The dollar was authorized by the Bland–Allison Act. Following the passage of the 1873 act, mining interests lobbied to restore free silver, which would require the Mint to accept all silver presented to it and return it, struck into co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Silver Eagle
The American Silver Eagle is the official silver bullion coin of the United States. It was first released by the United States Mint on November 24, 1986. It is struck only in the one-troy ounce, which has a nominal face value of one dollar and is guaranteed to contain one troy ounce of 99.9% pure silver. It is authorized by Title II of Public Law 99-61 (Liberty Coin Act, approved July 9, 1985) and codified as (e)-(h). Its content, weight, and purity are certified by the United States Mint. In addition to the bullion version, the United States Mint has produced a proof version and an uncirculated version for coin collectors. The Silver Eagle has been produced at three mints: the Philadelphia Mint, the San Francisco Mint, and the West Point Mint. The American Silver Eagle bullion coin may be used to fund Individual Retirement Account investments. Design The design on the coin's obverse was taken from the "Walking Liberty" design by Adolph A. Weinman, which originally had be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
