Precious metals are naturally-occurring metallic elements that are relatively rare and have high economic value due to their unique characteristics, features and uses. Precious metals tends to be less chemically reactive than other metals and are able to withstand corrosion well. These properties make precious metals an attractive choices for jewelry and investment sources. Over time, the list of precious metals can be subject to change as variables such extraction methods and available quantities may vary over time.

Sometimes precious metals are mixed with other elements to form an alloy. An alloy refers to a mixture or combination of two or more chemical elements of which at least one is a metal. Alloys retain the properties of the metal in the final material (e.g. luster and conductivity). However, alloys can have properties that are different from the properties of pure metals (e.g. hardness). Examples of alloys are:

White gold
White gold is an alloy that consists of gold mixed with at least one white metal. Usually, white gold contains silver, nickel or palladium.

Sterling silver
Sterling silver is an alloy that is made from silver mixed with another metals, usually being copper. The weight of sterling silver consists for 92,5% out of silver and 7,5% out of other metals.

Brass
Brass is an alloy made from copper and zinc with sometimes small portions of additional elements. The proportions of the metals may vary per alloy in order to achieve different results.

Bronze
Bronze is an alloy that usually consists of copper and is commonly mixed with tin. Often, other metals (e.g. nickel or zinc) or sometimes non-metals (e.g. phosphorus or arsenic) are also added to the alloy.

Over the course of history, precious metals have often been used for jewelry making and as a form of currency or investment. In modern times, precious metals have both aesthetic, industrial and economical uses. Nowadays, precious metals are mainly used in three areas:

1. Jewelry
2. Industrial processing
3. Investment

Fineness refers to the proportion of pure metal present in an alloy. Usually, fineness is expressed in parts per thousand. For example, 999 indicates that a metal is 99.9% pure. The fineness of alloy is often used to decide if an alloy can bear the name of the precious metal or not (e.g. what fineness value is required for gold to be considered gold). The fineness standards can differ per country, this means that for example what is marked as “gold” in country A is not necessarily marked as “gold” in country B.

Testing of precious metals is crucial to correctly identify the exact composition and therefore value of the pieces. There are a variety of methods used to identify precious metals, some of these methods include: 

Scratch And Acid Test
The scratch and acid test includes using a touchstone to scratch of a piece of metal. Next, different types of acid are poured into the scratched area to determine the karat (i.e. fineness or purity). This is one of the more common tests but has some objections to it. For example, the scratched area can leave a mark on some metals and some of the actual metal is rubbed off and lost.

Fire Assay
Fire assay is a testing method that involves melting a piece of precious metal to separate its contents. Despite that fire assay is considered a precise method, it is a destructive testing method as a part of the precious metal has to be melted in order to determine the concentration of the precious metal.

Lab Analysis
There are certain options to conduct testing in a laboratory with expensive machines. However, in many cases this is not the most practical solution.

Magnetism Test
Precious metals such as gold, silver and platinum are not magnetic. Therefore, it is recommended to hold a strong magnet next to the metal to see if its magnetic or not.

Feel
Precious metals have a different feel. Feel can be related to the softness and warmness of touch. For example, pure gold feel rather soft and silver feels warm because it absorbs heat quickly.

Sound
Some precious metals have distinct sounds that make it possible to identify them this. For example, pure gold makes a different sound from gold mixed with other metals.

Hallmarks
Typically, precious metals have specific markings indicating properties such as purity, weight or origin. For jewelry, the hallmarks are usually placed at discreet locations such as clasp or closure. Additionally, with bars and ingots, hallmarks or required markings are generally located at the top of the piece.

The list of precious metals below can be subject to change.

Symbol                   Precious Metal

Be                           Beryllium

Bi                            Bismuth

Ga                           Gallium

Ge                           Germanium

Au                           Gold

In                             Indium

Ir                              Iridium

Hg                           Mercury

Os                           Osmium

Pd                           Palladium

Pt                            Platinum

Re                           Rhenium

Rh                           Rhodium

Ru                           Ruthenium

Ag                           Silver

Te                           Tellurium

Precious metals are scarce, naturally-occurring metallic elements with high economic value. Sometimes precious metals are combined into an alloy, which is a mixture of two or more chemical elements of which at least one elements is a metal. The fineness of a precious metal refers to the proportion of pure metal present in an alloy. Different precious metals have different uses, however most precious metals are used in jewelry, industrial processing or investment.