Pure gold, in its elemental form, is not magnetic and will not stick to a magnet. This lack of attraction is due to its specific atomic structure and how its electrons interact with an external magnetic field. Understanding this property requires looking at the science of magnetism, which explains why certain metals react strongly while gold does not. The weak magnetic response gold does exhibit is virtually impossible to detect without specialized laboratory equipment.
The Magnetic Classification of Pure Gold
Pure gold (Au) is classified as a diamagnetic material. When placed within an external magnetic field, it develops a very weak opposing magnetic field, resulting in a slight repulsive force. This means pure gold is actually pushed away from a strong magnet rather than being attracted to it.
The reason for this behavior lies in the configuration of gold’s electrons, which are all paired up within their atomic orbitals. Paired electrons spinning in opposite directions cancel out their individual magnetic moments, resulting in no net magnetic moment for the atom. When an outside magnetic field is introduced, it causes a small, temporary shift in the electron’s motion, generating the minute opposing field. This diamagnetic repulsion is insignificant and not noticeable when testing 24-karat gold with a common handheld magnet.
Types of Material Magnetism
To appreciate gold’s non-magnetic nature, it is helpful to understand the three main ways materials interact with magnetic fields. The strongest type is ferromagnetism, characteristic of metals like iron, nickel, and cobalt. These materials are strongly attracted to magnets because their atomic magnetic moments spontaneously align into large regions called domains, creating a powerful overall magnetic effect. Ferromagnetic substances can also retain their magnetism after the external field is removed, leading to permanent magnets.
A second category is paramagnetism, where materials like aluminum and platinum show a weak attraction to a magnetic field. These materials contain unpaired electrons that act like tiny magnets, aligning weakly with an external field. This attraction is extremely faint and disappears immediately once the magnet is taken away. The third category is diamagnetism, which describes gold and is defined by the weak repulsion from a magnetic field.
The distinct behaviors of these three categories are rooted in the arrangement of electrons within the atoms. Ferromagnetic and paramagnetic materials have unpaired electrons that contribute to an attractive force. Conversely, diamagnetic materials like gold have all their electrons paired, leading to the slight, opposite-direction magnetic moment when exposed to a field. This difference in electron configuration helps distinguish pure gold from some other metals using a magnet test, though the test is not definitive.
Why Some Gold Objects Show Magnetic Attraction
While pure 24-karat gold is diamagnetic and will not stick to a magnet, many “gold” objects, particularly jewelry, are alloys. Gold is often combined with other metals to increase its hardness and durability, as pure gold is too soft for everyday wear. The magnetic properties of a gold object can change significantly depending on what other metals are present in the alloy.
Common alloying metals include copper and silver, which, like gold, are non-magnetic. However, other metals mixed into gold, such as nickel, cobalt, or iron, are strongly ferromagnetic. If a piece of jewelry, such as 14-karat or 10-karat gold, contains a sufficient percentage of these magnetic metals, it can exhibit an attraction to a magnet. For example, white gold often contains nickel, and the presence of this metal can cause a magnetic response.
Attraction to a magnet may also indicate that the item is a counterfeit or simply gold-plated, with a core made of a cheap, ferromagnetic metal like steel. Even genuine gold pieces can be attracted if they contain small steel springs or pins in clasps or hinges. Therefore, a magnetic response indicates that a gold item is not pure. However, a lack of response does not automatically confirm purity, as many non-magnetic metals are also used in alloys and fakes.