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When it comes to determining whether a diamond is real or not, diamond testers are often the first tool used by jewelers and buyers alike. These handheld devices claim to quickly and accurately test the authenticity of a diamond, but just how reliable are they? At Stirling’s Corner Fine Jewelry, we understand the importance of being well-informed when purchasing diamonds. In this blog, we’ll explore how diamond testers work, their accuracy, and any limitations they may have.

How Do Diamond Testers Work?

Diamond testers primarily work by measuring thermal conductivity. Diamonds are excellent conductors of heat, meaning they can quickly disperse heat when exposed to high temperatures. A diamond tester uses a small metal probe that touches the stone’s surface and gauges how quickly heat is transferred through the stone. If the tester detects a high level of thermal conductivity, it indicates that the stone is likely a diamond.

Types of Diamond Testers

There are generally two types of diamond testers:

  • Thermal Conductivity Testers: These are the most common and measure how well the stone conducts heat. They are effective for testing diamonds and moissanite, but less reliable for other stones.
  • Electrical Conductivity Testers: Some modern testers combine thermal and electrical conductivity tests to detect stones like moissanite, which can be mistaken for diamonds due to their similar thermal properties.

Accuracy of Diamond Testers

While diamond testers are accurate when used properly, there are some factors that can affect their reliability. Let’s break down how accurate these tools can be and what to consider when using one.

1. Reliable for Natural Diamonds

Diamond testers are highly reliable when it comes to detecting natural diamonds. Since diamonds are among the best conductors of heat, a diamond tester can almost always correctly identify a natural diamond from other common gemstones, such as cubic zirconia or glass. If the stone conducts heat as expected, the tester will give a positive result, confirming that the stone is indeed a diamond.

2. Potential Confusion with Moissanite

One limitation of traditional thermal diamond testers is their inability to distinguish between diamonds and moissanite. Moissanite, a popular diamond alternative, has thermal conductivity properties very similar to diamonds, which can cause standard diamond testers to incorrectly identify it as a diamond.

To address this, some newer testers combine both thermal and electrical conductivity tests. Moissanite conducts electricity differently than diamonds, so this additional test helps differentiate between the two stones, providing a more accurate reading.

3. False Negatives with Lab Grown Diamonds

Diamond testers are also reliable for lab grown diamonds, as they are real diamonds with the same chemical and physical properties as natural diamonds. However, some testers may produce false negatives with certain lab grown diamonds, particularly if the device is not calibrated correctly or is outdated. Most modern testers are equipped to handle both natural and lab grown diamonds, but it’s always a good idea to use a high-quality, up-to-date tester for the best results.

4. Temperature Sensitivity

Another factor that can affect the accuracy of diamond testers is temperature sensitivity. If the diamond is too cold or too hot, it may not conduct heat as expected, leading to an inaccurate reading. It’s essential to ensure that the stone and the surrounding environment are at a stable room temperature for the most accurate results.

Diamond Testers and Other Gemstones

While diamond testers are quite effective at identifying diamonds, they are less reliable when it comes to testing other gemstones. Here’s how they perform with some common diamond alternatives:

  • Cubic Zirconia (CZ): Diamond testers are very effective at identifying cubic zirconia, as CZ does not conduct heat like diamonds do. A diamond tester will almost always correctly identify cubic zirconia as a non-diamond.
  • White Sapphire: White sapphires, another popular diamond alternative, are poor conductors of heat. A diamond tester will easily distinguish a white sapphire from a diamond.
  • Moissanite: As mentioned earlier, moissanite can be tricky for thermal conductivity testers to distinguish from diamonds due to its similar properties. A tester that measures both thermal and electrical conductivity is more effective in identifying moissanite accurately.

When to Use a Diamond Tester

Diamond testers are best used in combination with other methods to ensure accurate identification of diamonds. Here are some situations where using a diamond tester is highly effective:

  • Initial Testing: A diamond tester is an excellent tool for a quick and straightforward identification. If you want to check whether a stone is likely a diamond, a diamond tester offers a fast way to get a reliable answer.
  • Retail Settings: Jewelers and retail stores often use diamond testers to quickly confirm the authenticity of a diamond for potential buyers. It’s a reliable first step when determining a stone’s legitimacy.
  • Personal Use: For those purchasing diamond jewelry or inheriting diamond pieces, having access to a diamond tester can help ensure the authenticity of your stone before making a significant investment.

Limitations of Diamond Testers

While diamond testers are valuable tools, they do have certain limitations that are important to understand:

  • Cannot Detect Clarity or Quality: Diamond testers can only confirm whether or not a stone is a diamond. They do not provide any information about the diamond’s clarity, cut, color, or overall quality. For these factors, a professional jeweler’s assessment is necessary.
  • Need for Additional Verification: Even if a diamond tester confirms the stone is a diamond, further verification might be required. For example, to ensure it’s not a high-quality imitation like moissanite, an additional electrical conductivity test may be needed.
  • Improper Use: Like any tool, diamond testers can give inaccurate readings if not used properly. It’s important to follow the manufacturer’s guidelines for best results, including ensuring the stone and device are at room temperature and properly calibrated.

Conclusion: Are Diamond Testers Accurate?

In general, diamond testers are accurate for identifying whether a stone is a diamond, especially when used under the right conditions. They excel at distinguishing diamonds from most common imitations like cubic zirconia and white sapphire. However, they may struggle with moissanite and require proper handling and calibration for lab grown diamonds.

At Stirling’s Corner Fine Jewelry, we always recommend using diamond testers as one part of a broader evaluation process. For a truly accurate assessment of your diamond’s authenticity and quality, a professional jeweler’s expertise is essential. Visit us today for expert advice, diamond testing, and access to our exquisite collection of diamonds and fine jewelry.