When it comes to confirming the authenticity of a diamond—especially one you’ve just purchased—you may find yourself asking: Can a lab grown diamond pass a diamond tester? It’s a fair and increasingly common question as lab diamonds grow in popularity. At Goldsmith Jewelers, we believe an informed customer is a confident customer, so let’s explore the tools, facts, and misconceptions behind this modern topic.
What Is a Diamond Tester—and How Does It Work?
A diamond tester is a handheld device used to determine whether a stone is a real diamond based on how it conducts heat or electricity.
Most diamond testers fall into two categories:
- Thermal conductivity testers — Measure how quickly heat passes through the stone.
- Electrical conductivity testers — Often used in combination (dual testers), as certain gemstones like moissanite conduct heat similarly to diamonds.
Did You Know?
Thermal testers were invented in the 1970s as a practical way to distinguish diamonds from imitations like cubic zirconia.
So, Do Lab Diamonds Pass the Test?
Yes—lab grown diamonds pass a diamond tester. That’s because they’re chemically and structurally identical to natural diamonds. Whether a diamond was formed over millions of years beneath the Earth or created in a lab over weeks, it will still exhibit the same:
- Thermal conductivity
- Refractive index
- Electrical insulation properties
In short, diamond testers can’t tell the difference. A lab diamond will test positive on both thermal and dual diamond testers—just like its natural counterpart.
What Diamond Testers Can’t Do
While diamond testers are useful, there are limits to their capabilities:
- They can’t tell the origin of the diamond (natural vs. lab).
- They can’t determine quality (cut, color, clarity, carat).
- They can’t spot clarity enhancements or treatments.
This is where GIA certification and working with a reputable jeweler—like Goldsmith Jewelers—comes into play.
How Reliable Are Diamond Testers?
Diamond testers are very reliable—but not foolproof. Here’s what to know:
- Thermal-only testers can sometimes mistake moissanite for a diamond.
- Dual testers greatly improve accuracy.
- Battery level, tip cleanliness, and room temperature can affect results.
As you can see, lab diamonds are indistinguishable from natural diamonds on both types of testers. Other stones—like moissanite or white sapphire—may pass on thermal testers, but not on dual testers.
Expert Tip: When in doubt, a certified jeweler can perform additional testing, such as UV fluorescence analysis, spectroscopy, or advanced lab testing.
What’s the Best Way to Verify a Lab Diamond?
If you want full peace of mind, look beyond the tester:
- Ask for a grading report from GIA, IGI, or GCAL
- Examine the laser inscription on the diamond’s girdle
- Work with a trusted jeweler who offers complete transparency
At Goldsmith Jewelers, our lab grown diamonds come with full disclosure, grading certificates, and expert guidance. We help you choose with confidence—every time.
Frequently Asked Questions
What kind of diamond tester do I need?
If you’re testing at home, a dual tester (thermal + electrical) is best, especially to differentiate diamonds from moissanite. For precise verification, consult a professional jeweler or gemologist.
Will moissanite pass a diamond tester?
It depends. Moissanite often passes thermal testers but will typically fail an electrical conductivity test. That’s why dual testers are more reliable for identifying this popular diamond alternative.
How accurate are diamond testers?
- Thermal testers are 90–99% accurate for differentiating diamonds from imitations.
- Dual testers increase accuracy for separating moissanite from diamonds.
For full confidence, a GIA-certified gemologist should evaluate your stone.
Is it possible for a real diamond to fail a tester?
Yes, but it’s rare. If the stone is very dirty, mounted in metal that interferes with conductivity, or tested in extreme temperatures, the result may be inconclusive or inaccurate.
Visit Us in North Royalton, OH
When you’re shopping for a diamond—natural or lab grown—trust the experts. At Goldsmith Jewelers, we combine generations of experience with modern technology to help you make the right choice.
Goldsmith Jewelers
12861 State Road,
North Royalton, Ohio 44133
440.237.4500
✉️ info@goldsmithjewelersohio.com
Tues–Fri: 10am–5:30pm
Sat: 10am–3pm | Sun & Mon: Closed
Why Choose Goldsmith Jewelers?
- In-house GIA-trained gemologists
- Hand-selected diamonds and lab grown options
- Custom design and remounting specialists
- Jewelry and watch repair services
- Transparent pricing and honest advice
Discover the perfect diamond—lab or natural—today.