The magnet test is a common, quick method used to check if a piece of gold is genuine. Gold is a valuable precious metal, making it a frequent target for counterfeiting using similar-looking base metals. When buying or inheriting jewelry or bullion, knowing how to spot a fake is an important first step in verification. Understanding the fundamental physical properties of gold helps determine whether a magnetic reaction confirms or denies its authenticity.
Gold’s Magnetic Properties
Pure gold (24-karat gold) is non-magnetic in any practical sense. Gold is classified as a diamagnetic material, meaning it generates a weak repulsive force when placed in a magnetic field. This repulsion is so subtle that it is imperceptible during a simple home test, even when using a strong rare-earth magnet. For a quick check, real gold will exhibit absolutely no attraction to the magnet.
This lack of attraction stems from the arrangement of electrons within the gold atoms. Diamagnetic materials do not have unpaired electrons that align to create a strong magnetic moment, unlike ferromagnetic metals such as iron. If a piece of gold jewelry or a gold bar is strongly drawn to a magnet, it is a clear indication that the item is not pure gold. The magnet test serves as an effective initial filter because an authentic, solid gold item will not stick.
Why “Gold” Jewelry May Be Magnetic
If a piece of jewelry marked as gold does stick to a magnet, the attraction is typically due to the presence of other metals mixed into the gold. Gold used in jewelry is often alloyed with different metals to increase its hardness and durability, since pure gold is very soft. Lower-karat gold, such as 10K or 14K, contains a higher percentage of these non-gold metals.
Some of the metals used in these alloys, including nickel, iron, or cobalt, are strongly ferromagnetic. When present in significant amounts, these metals may cause the jewelry to display a slight magnetic attraction. For example, white gold is often alloyed with nickel, which can introduce a minor magnetic response.
A strong, undeniable pull, however, suggests a more serious issue than just a low-karat alloy. This usually indicates the item is either gold-plated over a base metal core (like iron or steel) or is entirely counterfeit.
Other Simple Authenticity Checks
Since some non-magnetic metals are also used in fake gold, the magnet test alone is not entirely foolproof. Other simple checks are useful for verification.
Density Test
One of the most reliable at-home methods is the density test, which relies on gold’s exceptional heaviness. Gold has a density of approximately 19.3 grams per cubic centimeter, significantly higher than most common counterfeiting materials. A simple density check involves seeing how the item reacts to water; genuine gold will sink immediately and rapidly due to its weight. If the item floats or sinks slowly, its density is too low to be solid gold. This is useful because materials like copper or brass, which are also non-magnetic, are much lighter than gold.
Hallmarks and Markings
Examine the item for official markings or hallmarks. Authentic gold jewelry typically has a stamp indicating its purity, such as 10K, 14K, 18K, or 24K. Counterfeit or plated items often have markings stamped on them indicating they are not solid gold, such as “GP” (Gold Plated), “GF” (Gold Filled), or “HGE” (Heavy Gold Electroplate).
Ceramic Scratch Test
A final non-destructive test is the ceramic scratch test, which uses an unglazed ceramic surface to check the metal’s true color. Gently dragging the gold item across the ceramic will leave a streak of powder. Real gold leaves a distinct yellow or gold-colored streak, whereas fake gold or base metals often leave a black or green mark.