How to Determine if a Magnet is a Neodymium Magnet

Neodymium magnets, often referred to as NdFeB (Neodymium-Iron-Boron) magnets, are the strongest type of permanent magnet commercially available. Because they are used in everything from high-end electronics to industrial machinery, it is important to know exactly what you are dealing with.

If you have a mystery magnet and need to confirm if it is a "Rare Earth" neodymium magnet or a standard ferrite/ceramic one, you can use the following physical and performance indicators to make a determination.

1. Observe the Physical Appearance and Coating

The most immediate giveaway of a neodymium magnet is its finish. Unlike traditional magnets, neodymium is highly susceptible to corrosion and oxidation. To prevent this, manufacturers almost always apply a protective layer.

Metallic Shine: Most neodymium magnets are electroplated with a layer of nickel-copper-nickel, giving them a shiny, silver, or chrome-like appearance.

Other Coatings: While silver is the standard, they may also be coated in gold, black epoxy, or even colorful plastic/rubber.

Contrast with Ferrite: If the magnet is dark grey or charcoal-colored and feels slightly "chalky" or matte, it is likely a Ferrite (Ceramic) magnet, not neodymium.

2. Test the Magnetic Strength

Neodymium magnets are legendary for their incredible "pull force" relative to their size. A small neodymium disc can often hold significantly more weight than a ferrite magnet five times its size.

The Fridge Test: A small neodymium magnet will be remarkably difficult to pull straight off a refrigerator door. You will likely need to slide it to the edge to remove it.

The Paper Stack Test: Try to see how many sheets of paper the magnet can hold against a metal surface. A neodymium magnet will usually penetrate a thick stack (20+ sheets), whereas a standard magnet will fail after a few pages.

Interaction with Other Magnets: If you bring two neodymium magnets near each other, the pull will be sudden and violent. Exercise caution: Large neodymium magnets can pinch skin or even shatter upon impact.

3. Assess the Weight and Density

Neodymium magnets are surprisingly heavy for their size because they are made of dense rare-earth elements and iron.

Density Check: Neodymium magnets have a density of approximately 7.4 to 7.5 g/cm³.

Comparison: If you have two magnets of identical size—one neodymium and one ceramic—the neodymium one will feel significantly heavier in your hand. Ferrite magnets are much lighter and feel "stonelike."

4. Check for Brittleness and Durability

Despite their immense strength, neodymium magnets are structurally fragile. They are more like "metallic glass" than solid steel.

Impact Sensitivity: If a neodymium magnet is dropped on a hard surface or allowed to snap against another magnet, it will often chip, crack, or shatter into sharp shards.

Internal Material: If you see a chip in the coating, the material underneath should look like a dull, dark grey crystalline metal. If the material is black and crumbly throughout, it is ceramic.

5. Thermal Sensitivity

While this is harder to test without specialized equipment, neodymium magnets are notoriously sensitive to heat.

Standard Grade: Most standard neodymium magnets (N-rated) begin to lose their magnetic strength permanently if heated above 80°C (176°F).

Samarium Cobalt Comparison: If a magnet remains powerful even at extremely high temperatures (up to 300°C), and it is shiny, it might be a Samarium Cobalt magnet, which is another type of rare earth magnet, though these are less common in household items.

Summary Checklist

To confirm you have a neodymium magnet, look for these "Big Three" markers:

A shiny, metallic plated finish (usually nickel).

Extremely high pull force for its small size.

High brittleness (it chips rather than dents).

Safety Warning: Neodymium magnets are not toys. They can interfere with pacemakers, erase magnetic media (like credit cards), and cause serious internal injury if more than one is swallowed. Always handle with care.