Coin collecting in the context of United States dollar coin

In monetary economics, the currency in circulation in a country is the value of currency or cash (banknotes and coins) that has ever been issued by the country’s monetary authority less the amount that has been removed. More broadly, money in circulation is the total money supply of a country, which can be defined in various ways, but always includes currency and also some types of bank deposits, such as deposits at call.

The published amount of currency in circulation tends to be overstated by an unknown amount. For example, money may have been destroyed, or stored as a form of security (the proverbial “money under the mattress”), or by coin collectors, or held in reserve within the banking system, including currency held by foreign central banks as a foreign exchange reserve asset.

A gold coin is a coin that is made mostly or entirely of gold. Most gold coins minted since 1800 are 900–920 ‰ gold (22‑karat), while most of today's gold bullion coins are pure gold, such as the Britannia, Canadian Maple Leaf, and American Buffalo. Alloyed gold coins, like the American Gold Eagle and South African Krugerrand, are typically 917 ‰ gold by weight, with the remainder being silver and copper.

Until about the 1930s, gold coins were circulation coins, including coin-like bracteates and dinars. Since then, gold coins have mainly been produced as bullion coins for investors and as commemorative coins for collectors. While modern gold coins are still legal tender, they are not used in everyday financial transactions, as the metal value invariably exceeds the nominal value. For example, the quarter-ounce American Gold Eagle has a denomination of $10, but a metal value of approximately $500 (as of January 2024).

The dollar coin is a United States coin with a face value of one United States dollar. Dollar coins have been minted in the United States in gold, silver, and base metal versions. Dollar coins were first minted in the United States in 1794.

Dollar coins have almost never been popular in circulation since their inception. Despite efforts by the U.S. government to promote their use to save the cost of printing one dollar bills, the Anthony Dollar, the Sacagawea Dollar and the Presidential Dollar Series are all seldom seen in circulation, since most Americans prefer to use the dollar bill. For this reason, since December 11, 2011, the Mint has not produced dollar coins for general circulation, and all dollar coins produced after that date have been specifically for collectors. These collector coins can be ordered directly from the Mint, while pre-2012 circulation dollars can be obtained from most U.S. banks.

Pendilia (singular pendilium; from Latin pendulus, hanging) or pendoulia (the Greek equivalent), are pendants or dangling ornaments hanging from a piece of metalwork such as a crown, votive crown, crux gemmata, or kamelaukion, and are a feature of Early Medieval goldsmith work. On crosses the pendilia may include the letters alpha and omega, and on votive offerings, which were often designed to be hung over altars and where pendilia are at their largest and most spectacular, they may spell out whole words (see illustration).

The term is commonly used in coin collecting. Pendilia are depicted on coins as jewels or pearls hanging from the sides of the crown, and occur frequently on coins of Byzantine emperors. The pendilia which hung from the Emperors' crowns began with Marcian. Although the years saw the styles of crown change, the pendilia remained, at least through Manuel II Palaiologos. Surviving crowns with pendilia include the Holy Crown of Hungary and many votive crowns of the Treasure of Guarrazar from Visigothic Spain.

An alternative investment, also known as an alternative asset or alternative investment fund (AIF), is an investment in any asset class excluding capital stocks, bonds, and cash.

The term is a relatively loose one and includes tangible assets such as precious metals, collectibles (art, wine, antiques, vintage cars, coins, watches, musical instruments, or stamps) and some financial assets such as real estate, commodities, private equity, distressed securities, hedge funds, exchange funds, carbon credits, venture capital, film production, financial derivatives, cryptocurrencies, non-fungible tokens, and Tax Receivable Agreements. Investments in real estate, forestry and shipping are also often termed "alternative" despite the ancient use of such real assets to enhance and preserve wealth. Alternative investments are to be contrasted with traditional investments.

The American Platinum Eagle is the official platinum bullion coin of the United States. In 1995, Director of the United States Mint Philip N. Diehl, American Numismatic Association President David L. Ganz, and Platinum Guild International Executive Director Jacques Luben began the legislative process of creating the Platinum Eagle. After over two years of work, the 99.95% fine platinum coins were released by the United States Mint in 1⁄10, 1⁄4, 1⁄2 and 1 troy oz denominations. In late 2008, the fractional denominations were discontinued, leaving only the one ounce denomination. The Platinum Eagle is authorized by the United States Congress, and is backed by the United States Mint for weight, content, and purity. Its obverse was designed by John Mercanti, and portrays the Statue of Liberty (Liberty Enlightening the World) by Frédéric Auguste Bartholdi.

Proof versions of the coins are intended for coin collectors and sold directly to the public whereas the bullion versions are sold only to the Mint's authorized buyers. The proof American Platinum Eagles are unique in the fact that they are the only U.S. bullion coins that have a yearly alternating design. Bullion versions are minted with the same design every year. While minted, the uncirculated Platinum Eagles matched the proof designs and were struck on burnished coin blanks with a "W" mint mark signifying West Point, further distinguishing them from the bullion versions.

Platinum coins are a form of currency. Platinum has an international currency symbol under ISO 4217 of XPT. The issues of legitimate platinum coins were initiated by Spain in Spanish-colonized America in the 18th century and continued by the Russian Empire in the 19th century. As a form of currency, these coins proved to be impractical: platinum resembles many less expensive metals, and, unlike the more malleable and ductile silver and gold, it is very difficult to work. Several commemorative coin sets have been issued starting from 1978 and became popular among coin collectors. The major platinum bullion coins include the American Platinum Eagle, the Canadian Platinum Maple Leaf, the Australian Platinum Koala, the Manx Noble, the Chinese Platinum Panda, the Austrian Vienna Philharmonic and several series by the Soviet Union and later by the Russian Federation.