Carat (purity) in the context of "Precious metal"

Gold leaf is gold that has been hammered into thin sheets (usually around 0.1 μm thick) by a process known as goldbeating, for use in gilding.

Gold leaf is a type of metal leaf, but the term is rarely used when referring to gold leaf. The term metal leaf is normally used for thin sheets of metal of any color that do not contain any real gold. Gold leaf is available in a wide variety of karats and shades. The most commonly used gold is 23-karat gold.

The American Buffalo, also known as a gold buffalo, is a 24-karat bullion coin first offered for sale by the United States Mint in 2006. The coin follows the design of the Indian Head nickel and has gained its nickname from the American Bison on the reverse side of the design. This was the first time the United States government minted pure (.9999) 24-karat gold coins for the public. The coin contains one-troy ounce (31.1g) of pure gold and has a legal tender (face) value of US$50. Due to a combination of the coin's popularity and the increase in the price of gold, the coin's value has increased considerably. The initial 2006 U.S. Mint price of the proof coin was $800. In 2007 the price was $899.95, $1,410 in 2009, $2,010 in 2011, and $3,590 in 2024.

In addition to requiring a presidential dollar coin series to begin in 2007 and redesigning the cent in 2009, the Presidential $1 Coin Act of 2005 mandated the production of a one-ounce 24-karat gold bullion coin with a face value of $50 and a mintage limit of up to 300,000 coins.

White gold is an alloy of gold and at least one white metal, usually nickel or palladium. Like yellow gold, the purity of white gold is given in carats (karats). It is often used on jewellery.

A common white gold formulation consists of 90% wt. gold and 10% wt. nickel. Copper can be added to increase malleability.

The golden spike (also known as the last spike) is the ceremonial 17.6-karat gold spike driven to mark the completion of the first transcontinental railroad across the United States. It was driven by Leland Stanford to connect the Central Pacific Railroad from Sacramento and the Union Pacific Railroad from Omaha on May 10, 1869, at Promontory Summit, Utah Territory. The spike is now displayed in the Cantor Arts Center at Stanford University.

The term last spike has since been used to refer to a spike driven at the usually ceremonial completion of a railroad construction project, particularly one in which construction is undertaken from two origins toward a meeting point.