You can identify fake gold using simple tests like the scratch test and density measurement.
Authentic gold has unique physical properties that distinguish it from other metals commonly used in fake jewelry or items. Knowing how to perform a few basic tests can help you determine if a piece is genuine gold or just appears to be.
Here are some methods to consider:
1. The Scratch Test
This is a common and relatively quick test, though it requires a specific tool (an unglazed ceramic surface).
- How to do it: Gently rub the piece of gold against an unglazed ceramic plate or tile. Apply slight pressure to create a mark.
- What to look for:
- Genuine gold will leave a golden streak on the ceramic surface.
- Fake gold may leave a black mark due to other metals mixed in. This black streak indicates that the material is likely not pure gold or a high-karat alloy. Other metals like brass, iron, or pyrite (often called "fool's gold") will produce a different color streak, often black or greenish-black.
Important Note: This test can slightly damage the item, so use caution, especially with valuable or delicate pieces.
2. Density Measurement
Gold is a very dense metal. Measuring the density of a piece can give a strong indication of its authenticity.
- How to do it:
- First, weigh the gold item accurately (e.g., in grams).
- Next, measure its volume. The easiest way for irregular shapes is using water displacement:
- Fill a container with water and note the initial water level or weight.
- Submerge the gold piece completely and note the new water level or weight.
- The difference in water level (in milliliters) or weight (in grams, as 1 gram of water = 1 ml) is the volume of the gold piece (in cm³ or ml).
- Calculate density using the formula: Density = Mass / Volume.
- What to look for: Pure 24K gold has a density of approximately 19.3 g/cm³. Lower karat gold alloys will have slightly lower densities depending on the mixture. For example, 18K gold might be around 15.2–15.9 g/cm³, and 14K gold around 12.9–14.6 g/cm³. A material with a significantly different density is likely not gold.
| Material | Approximate Density (g/cm³) |
|---|---|
| 24K Gold | 19.3 |
| 18K Gold (Typical) | 15.2 – 15.9 |
| 14K Gold (Typical) | 12.9 – 14.6 |
| Tungsten | 19.3 (Can be used in fakes) |
| Lead | 11.3 |
| Brass | 8.4 |
| Iron | 7.8 |
Caveat: Some fake gold items, particularly sophisticated counterfeits, might use metals with densities close to gold, like tungsten (which has a very similar density to pure gold). Combining tests is always recommended.
Other Simple Checks
While the scratch and density tests are effective based on physical properties, other simple checks can offer clues:
- Magnet Test: Gold is not magnetic. If a strong magnet attracts the item, it's not gold. However, many non-gold metals are also not magnetic, so passing this test doesn't guarantee authenticity.
- Weight and Feel: Get familiar with the weight and feel of genuine gold jewelry. Gold is heavy for its size. If an item feels unusually light, it might be fake.
For certainty, especially with valuable items, consider consulting a professional jeweler or getting an assay test.
