Will Sapphire Pass a Diamond Tester? The Expert’s Verdict

No, sapphire will not pass a diamond tester designed to measure thermal conductivity. Diamond testers work by measuring how quickly heat dissipates through a gemstone. Diamonds are exceptional thermal conductors, while sapphires are not. Therefore, a diamond tester will reliably distinguish between the two.

Understanding Diamond Testers and Gemstone Identification

Diamond testers have become an indispensable tool for jewelers, gemologists, and even savvy consumers. But their effectiveness hinges on understanding what they actually measure and the limitations inherent in that measurement. To fully comprehend why sapphire won’t fool a diamond tester, we need to delve into the underlying science.

How Diamond Testers Work

Diamond testers, at their core, are thermal conductivity meters. They apply a small amount of heat to the gemstone and then measure how quickly that heat is conducted away. Diamonds, specifically natural diamonds, possess extraordinarily high thermal conductivity. This is due to their tightly bonded carbon atoms in a specific crystal lattice structure. The faster the heat dissipates, the higher the thermal conductivity reading, and the more likely the stone is a diamond.

Think of it like this: imagine touching a metal spoon versus a wooden spoon in a room at the same temperature. The metal spoon feels colder because it rapidly conducts heat away from your hand. Diamond testers operate on a similar principle, but with far more precise measurements.

The Thermal Conductivity of Sapphire

Sapphire, on the other hand, is a variety of the mineral corundum (aluminum oxide, or Al2O3). While still a hard and durable gemstone, its thermal conductivity is significantly lower than that of diamond. Its atomic structure simply isn’t as efficient at transferring heat.

Therefore, when a diamond tester is applied to a sapphire, the heat will not dissipate as quickly. The device will register a lower thermal conductivity reading, clearly indicating that the stone is not a diamond.

Other Gemstones and Diamond Testers

It’s crucial to note that diamond testers are primarily designed to distinguish diamonds from diamond simulants. Common simulants include cubic zirconia (CZ) and moissanite. CZ, in particular, has a very low thermal conductivity and will never be mistaken for a diamond by a standard tester.

Moissanite, however, presents a trickier situation. It possesses a thermal conductivity closer to diamond than sapphire. This led to the development of more advanced testers that can differentiate between diamond and moissanite based on slight differences in their thermal properties and electrical conductivity. These advanced testers are often referred to as moissanite testers or multi-testers.

Practical Implications: Avoiding Misidentification

Knowing that a sapphire won’t pass a diamond tester is crucial for both buyers and sellers. Here’s why:

• For buyers: A diamond tester provides a quick and relatively inexpensive way to verify if a stone being presented as a diamond is, in fact, a diamond. While it’s not foolproof (more on that later), it’s a valuable first line of defense against fraud.
• For sellers: Accurately identifying gemstones is paramount to ethical business practices. A diamond tester helps ensure that sapphires aren’t accidentally or intentionally misidentified as diamonds, protecting both the seller’s reputation and the buyer’s investment.

Limitations of Diamond Testers

While diamond testers are useful tools, they have limitations.

• Synthetic Diamonds: Lab-grown diamonds, also known as synthetic diamonds, possess essentially the same chemical composition and crystal structure as natural diamonds. As a result, they will pass a diamond tester. Distinguishing them requires more sophisticated gemological testing.
• Surface Coatings: In rare cases, a diamond simulant might be coated with a thin layer of diamond material. This coating could potentially fool a basic diamond tester, but the coating is easily damaged and wouldn’t hold up to closer inspection.
• Environmental Factors: Extremely cold or hot temperatures can slightly affect the accuracy of a diamond tester. It’s best to use the tester at room temperature.

The Importance of Professional Gemological Testing

Ultimately, a diamond tester is a screening tool, not a definitive identification method. For absolute certainty, especially with valuable gemstones, it’s essential to consult a certified gemologist. Gemologists utilize a range of instruments and techniques, including microscopic examination, refractive index measurements, and spectroscopic analysis, to accurately identify gemstones and assess their quality.

FAQs: Understanding Sapphire and Diamond Testing

Here are some frequently asked questions that further clarify the relationship between sapphire and diamond testers:

FAQ 1: Can a fake diamond pass a diamond tester?

Yes, some fake diamonds can pass a diamond tester. Specifically, lab-grown diamonds will register as diamonds because they are chemically and structurally identical to mined diamonds. Certain coated simulants might also temporarily fool a tester.

FAQ 2: What other tests can I use to identify sapphire?

Besides a diamond tester (to rule out diamond), you can identify sapphire based on its hardness (9 on the Mohs scale), refractive index (1.76-1.77), specific gravity (3.99-4.00), and microscopic inclusions. A gemologist can perform these tests accurately.

FAQ 3: Are all diamond testers the same?

No. There are basic thermal conductivity testers and more advanced multi-testers that can differentiate between diamond, moissanite, and other gemstones. The latter often measure electrical conductivity in addition to thermal conductivity.

FAQ 4: Can a sapphire scratch a diamond?

No. Diamond is the hardest known naturally occurring material (10 on the Mohs scale). Sapphire (9 on the Mohs scale) can be scratched by a diamond, but not the other way around.

FAQ 5: What is the most reliable way to test for a real diamond?

The most reliable way is to have the stone examined by a certified gemologist who can perform a comprehensive analysis using specialized equipment.

FAQ 6: Is it possible to get a false positive with a diamond tester?

It’s rare, but possible. A contaminated probe or a diamond simulant with a thin diamond coating could potentially produce a false positive, though temporarily.

FAQ 7: How much do diamond testers cost?

Diamond testers range in price from around $20 for basic models to several hundred dollars for more advanced multi-testers used by professionals.

FAQ 8: Can heat from a flame distinguish a real diamond?

While some people suggest this, it’s not a reliable or safe method. Exposing a gemstone to direct flame can damage it. Furthermore, some simulants can withstand heat without showing obvious signs of damage.

FAQ 9: Why is thermal conductivity important in gemstone identification?

Thermal conductivity is a distinctive property that helps differentiate between gemstones because each gemstone has a unique chemical composition and crystalline structure that affect its thermal conductivity.

FAQ 10: What are some common diamond simulants and how do they differ from diamonds?

Common diamond simulants include cubic zirconia (CZ), moissanite, and white sapphire. CZ has very low thermal conductivity, moissanite has a similar thermal conductivity to diamond but different electrical conductivity, and white sapphire is less brilliant and durable than diamond.

FAQ 11: Can a diamond tester detect treated diamonds?

A standard diamond tester primarily measures thermal conductivity and won’t reliably detect common diamond treatments like clarity enhancement or color enhancement. Specialized equipment is required for this.

FAQ 12: Can I use a diamond tester on mounted jewelry?

It can be tricky. If the metal setting is touching the stone, it can interfere with the reading and give a false result. It’s best to test unmounted stones.

In conclusion, while a diamond tester is a useful tool for preliminary gemstone screening, it is not a substitute for professional gemological analysis. Sapphire will not pass a diamond tester, but understanding the limitations of these devices is essential for accurate gemstone identification and avoiding misrepresentation. Always seek the expertise of a qualified gemologist for definitive identification and valuation.