Step By Step Guide To Testing A Moissanite Pendant With A Diamond Tester For Accurate Results

Moissanite has become a popular alternative to diamonds, prized for its brilliance, durability, and affordability. However, because it closely resembles a diamond in appearance, distinguishing between the two requires more than just visual inspection. Many jewelers and consumers rely on handheld diamond testers, but using them correctly—especially on moissanite—is critical to avoid misleading results. While some diamond testers may incorrectly identify moissanite as a diamond due to similar thermal conductivity, understanding the limitations and proper testing procedures ensures accuracy.

This guide walks through the science behind diamond testing, explains why moissanite can trick certain testers, and provides a reliable, step-by-step method to test your moissanite pendant with confidence.

Understanding Diamond Testers and Moissanite’s Properties

Diamond testers operate on one of two principles: thermal conductivity or electrical conductivity. Traditional testers measure how quickly heat moves through a stone. Diamonds are excellent heat conductors, so they disperse heat rapidly. Moissanite also conducts heat efficiently, which is why older or basic thermal testers often misidentify it as a diamond.

Modern multi-testers combine both thermal and electrical conductivity measurements. Moissanite is electrically conductive—a property diamonds lack—allowing advanced testers to differentiate between the two. If you're testing a moissanite pendant, using a dual-mode tester is essential for accurate identification.

“Many customers come in convinced their stone is a diamond because their old tester said so. The reality? That device couldn’t tell moissanite from diamond.” — Jordan Lee, GIA-Certified Gemologist

Tip: Always use a dual-mode (thermal + electrical) diamond tester when verifying moissanite or any diamond simulant.

Step-by-Step Testing Procedure

To ensure reliable results when testing a moissanite pendant, follow this systematic approach. Rushing or skipping steps can lead to false positives or damage to the jewelry.

1. Clean the Pendant Thoroughly
   Residue, oils, or dirt on the surface can interfere with the tester’s probe contact. Use a soft-bristled brush and mild dish soap in warm water. Rinse and dry completely with a lint-free cloth.
2. Power On and Calibrate the Tester
   Turn on the device and allow it to complete its self-calibration. Most testers will beep or display a ready signal. Refer to the user manual to confirm calibration success.
3. Verify Tester Function with a Known Diamond
   Test a confirmed diamond first to ensure the device is working properly. This eliminates equipment error as a factor.
4. Position the Pendant Securely
   Lay the pendant on a stable, non-conductive surface. Hold it gently with tweezers or place it in a ring holder if available. Avoid touching the stone directly during testing to prevent heat transfer from your fingers.
5. Apply the Probe Correctly
   Place the tester’s probe perpendicular to the crown (top) of the moissanite. Apply light, consistent pressure. Do not drag or slide the probe. Maintain contact for 2–3 seconds or until the reading stabilizes.
6. Interpret the Results
   A dual-mode tester will typically indicate either “Diamond,” “Moissanite,” or “Unknown.” If it reads “Moissanite” or beeps with a distinct tone (varies by model), the stone is moissanite. If it reads “Diamond,” double-check using additional methods (see below).
7. Repeat on Multiple Facets
   Test at least three different points on the stone’s surface to rule out anomalies caused by facet angle or internal inclusions.

Common Pitfalls and How to Avoid Them

Even experienced users can make mistakes when testing moissanite. Awareness of common errors improves accuracy.

Issue	Why It Happens	Solution
False positive (reads as diamond)	Using a thermal-only tester; moissanite conducts heat like diamond	Upgrade to a dual-mode tester that checks electrical conductivity
Inconsistent readings	Poor contact, dirty stone, or low battery	Clean the stone, check battery, retest with steady probe pressure
No reading or error message	Probe not making full contact or stone is set too deeply	Adjust angle, ensure metal setting isn’t interfering with contact
Damage to the pendant	Excessive pressure or abrasive probe tip	Use gentle pressure; inspect probe for wear regularly

Mini Case Study: A Misleading Reading Resolved

Sarah purchased a pendant online labeled as a “lab-created diamond.” Excited, she brought it to a local jeweler to verify its authenticity. The jeweler used an older thermal tester, which confirmed it as a diamond. Satisfied, Sarah wore it for months—until she visited a gemological lab for an appraisal.

The lab technician used a dual-mode tester and immediately identified the stone as moissanite. Upon further inspection, Sarah learned her original tester only measured heat dispersion and couldn’t detect electrical conductivity. While the stone was genuine moissanite and well-cut, the mislabeling caused confusion. This case underscores the importance of using the right tool and not relying solely on a single test.

Tip: When in doubt, seek verification from a certified gemologist or use a professional-grade tester.

Essential Checklist for Accurate Testing

• ✅ Use a dual-mode (thermal + electrical) diamond tester
• ✅ Clean the pendant before testing
• ✅ Calibrate the device according to manufacturer instructions
• ✅ Test a known diamond first to confirm device accuracy
• ✅ Hold the pendant securely without touching the stone
• ✅ Apply probe perpendicularly with light, steady pressure
• ✅ Record readings from multiple facets
• ✅ Consult a professional if results are unclear

Frequently Asked Questions

Can a diamond tester damage my moissanite pendant?

No, a properly used diamond tester will not damage moissanite. The probe applies minimal pressure and does not scratch the surface under normal conditions. However, excessive force or a worn probe tip could potentially cause micro-abrasions over time.

Why do some diamond testers say my moissanite is a diamond?

This happens with thermal-only testers because moissanite and diamond have similar thermal conductivity. These devices cannot detect the electrical conductivity unique to moissanite. Only dual-mode testers can reliably distinguish between the two.

Is moissanite considered a fake diamond?

No. Moissanite is a legitimate gemstone in its own right, not a counterfeit. It is lab-created silicon carbide with optical properties that rival diamonds. While it’s marketed as a diamond alternative, it has its own value and appeal.

Final Thoughts and Next Steps

Testing a moissanite pendant with a diamond tester can yield accurate results—if done correctly. The key lies in using the right equipment and following a disciplined process. Relying on outdated or single-function testers risks misidentification, which can affect insurance, resale value, and personal confidence in your jewelry.

Whether you're a consumer verifying a recent purchase or a jeweler serving clients, precision matters. Take the time to invest in a quality dual-mode tester, learn its functions, and apply best practices every time. When uncertainty remains, professional gemological services provide definitive answers.

💬 Have you encountered a surprising result when testing moissanite? Share your experience or questions below—your insight could help others avoid common pitfalls.