Does moissanite pass the diamond tester? Short answer: yes, in most cases it will. But the longer answer matters; can gemology tools and machines accurately tell the difference between diamonds and diamond simulants?
Moissanite can easily pass a standard diamond tester. Most diamond testers measure thermal conductivity, and moissanite conducts heat at almost the same rate as a real diamond. To tell them apart, you need a dual tester that also measures electrical conductivity; moissanite conducts electricity, diamond does not.
This blog post will outline the various diamond testers, unique attributes of moissanite vs. diamond, and how to spot the difference, answering any questions you may have and alleviating concerns. We will also walk through exactly how a moissanite diamond tester works, why moissanite tricks single-probe testers, and what you can do to verify your stone with certainty. Analyzing your moissanite ring or other jewelry is a helpful and rewarding step for appreciating its beauty.
Curious how moissanite holds up in real jewelry? Explore IceCartel's full moissanite collection.
Shop MoissaniteDoes Moissanite Pass a Diamond Tester?
Yes, most moissanite will pass a standard diamond tester. The reason is simple: nearly all common diamond testers measure how well a stone conducts heat (thermal conductivity), and moissanite happens to be one of the only gemstones besides diamond that conducts heat efficiently. To a basic thermal tester, the two stones look identical.
This applies to almost every moissanite stone, whether it is VVS-grade, set in a ring, or part of a chain. The stone’s grade or setting does not change the result. If you put a moissanite stone in front of a single-probe thermal diamond tester, it will read as a diamond.
What does NOT happen: cubic zirconia, glass, and most other diamond simulants fail the test immediately because they do not conduct heat the same way. Moissanite is the major exception.
The fix is straightforward: use a dual or multi-tester that also checks electrical conductivity. Moissanite is electrically conductive; diamond is not. A dual tester will distinguish them every time. We cover the full step-by-step verification process further down the page.
What is a Diamond Tester?
A moissanite diamond tester (the same device used to check diamonds) is a small handheld tool jewelers and buyers use to quickly assess whether a stone is a real diamond. Will moissanite pass a diamond tester? There are several methods used for testing a stone and determining if it is a diamond or not.
One of the common methods is a diamond tester. It may be used in conjunction with other gemological tests evaluating the stone.
A diamond tester works by measuring the diamond's thermal conductivity, electrical conductivity, fluorescence, and other attributes. Did you know there are many different types of diamond testers?
Types of Diamond Testers
Moissanite vs. diamond test; there are several kinds of diamond testers available in the market, each with its own attributes. Some of the common types of testers include heat, electricity, or combination testers. Here are is a breakdown of different testers:
Diamond tester pens
These are handheld devices that use electrical conductivity to detect whether a gemstone is a diamond or not. Pawnshops and jewelry stores often carry these types of testers; they are charged by plugging it into the wall. Diamond tester pens are inexpensive and may be purchased for at-home use. The tester goes to green or red, notating the results with a sound.
Special care must be taken not to touch the metal–diamond tester pens are sensitive and will emit an incorrect result. Pressing the tip flat against the stone with a small amount of pressure is optimal for receiving an accurate result.
Thermal conductivity testers
A thermal conductivity tester measures how quickly a material conducts heat and uses this information to determine whether a gemstone is a diamond or not. These testers are relatively inexpensive and easy to use, but they are not always accurate, as some diamond simulants can also conduct heat. Moissanite is the prime example. Its silicon carbide structure conducts heat almost identically to diamond carbon, which is exactly why moissanite passes a thermal tester.
Electrical conductivity testers
An electrical conductivity tester measures how well a material conducts electricity determining diamond and gemstone identification. Diamonds are poor conductors of electricity compared to many diamond simulants and stones. This is the test that separates moissanite from diamond. Moissanite is electrically conductive; diamond is not. A combination tester (thermal + electrical) catches the moissanite vs. diamond tester distinction every time.
Ultraviolet testers
Uses ultraviolet light to detect a diamond. Diamonds will fluoresce (emit a glowing light) under ultraviolet light, Ultraviolet testers are easy to use, but they can be less accurate than other types of testers, as some diamond simulants and stones can also fluoresce under ultraviolet light.
Why Does Moissanite Pass a Diamond Tester?
Moissanite passes a diamond tester because of one specific property: thermal conductivity. The reason comes down to crystal structure and physics, not faulty equipment.
Diamonds are made of pure carbon arranged in a tightly bonded crystal lattice. That structure makes them the best heat conductor among gemstones; heat moves through a diamond extremely fast. Standard diamond testers detect this by sending a tiny heat pulse into the stone and measuring how quickly it disperses.
Moissanite is made of silicon carbide (SiC), which has a different chemical makeup but a surprisingly similar crystal lattice. Silicon carbide conducts heat at almost the same rate as diamond. From the tester’s perspective, the heat signature is virtually identical. So it reads "diamond."
Other simulants do not have this problem. Cubic zirconia, glass, white sapphire, and most other diamond look-alikes have significantly lower thermal conductivity, so they fail the test instantly. Moissanite is the one major exception, which is why this question gets asked so often.
The bottom line: it is not the tester being wrong. The tester is doing exactly what it was designed to do — it just was not designed to distinguish moissanite from diamond. A combination thermal + electrical tester closes that gap.
What is Moissanite?
Natural moissanite was discovered in Arizona by Nobel Prize-winning chemist Dr. Henri Moissan in 1893, hence the name moissanite. Moissanite is found in extremely small quantities in certain types of rocks, such as kimberlites and lamproites, as well as in meteorites. This makes moissanite extremely expensive.
Because of its rarity, synthetic moissanite was created in a laboratory in the late 1990s. Moissanite is composed of silicon carbide (SiC), with a carbon atom surrounded by four silicon atoms in a tetrahedral form.
How Moissanite is Different From Diamond?
Can a diamond tester detect moissanite? Moissanite and diamonds are popular choices for engagement rings and other types of fine jewelry. While both stones may display incredible brilliance and fire with the untrained eye, they contain different physical and chemical properties. Here are some ways to notate the difference between moissanite and diamonds:
Why is Moissanite Used as a Diamond Alternative?
Moissanite vs diamond test; the choice between moissanite and diamonds is personal to the buyer. Factors including budget and personal stances on environmental impact play an important role in the purchasing decision. There are few reasons why moissanite is chosen in the place of diamond:
Difference Between Diamonds & Moissanite
Beyond the diamond test, moissanite and diamond can be distinguished using several other methods.Several other tests can be used to identify moissanite and diamonds, including:
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1Visual inspection: Moissanite has a distinctively different appearance than diamonds, with a higher level of brilliance and fire due to its higher refractive index and doubling. Moissanite can be distinguished from diamonds by the naked eye or by a jeweler's loupe.
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2Analyzing the inclusions: This is part of the visual inspection process. Diamonds contain distinctive growth characteristics as a result of the formation process. These inclusions (internal) and blemishes (external) are indicative of diamonds, analyzed by a jewelry professional.
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3Electrical conductivity test: Moissanite is electrically conductive, unlike diamonds. This difference can be distinguished by diamonds using an electrical conductivity tester.
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4Ultraviolet light test: Moissanite glows a different color than diamonds when exposed to ultraviolet light.
Can Moissanite Pass the Diamond Tester?
Moissanite passes a standard thermal diamond tester. The reason is its high thermal conductivity, which closely matches that of a real diamond. But moissanite does not contain the same chemical properties as diamond, and that becomes obvious the moment you use a more advanced test.
The moissanite tester vs. diamond tester comparison is important here: a single-probe thermal diamond tester cannot tell the difference between moissanite and diamond, but a dual-probe combination tester (thermal + electrical) can. Some manufacturers now sell dedicated "moissanite testers" that look identical to diamond testers but use electrical conductivity as their primary check; they will correctly flag moissanite as moissanite, not diamond. So:
| Test Method | Result with Moissanite |
|---|---|
| Single-probe thermal diamond tester | Reads moissanite as diamond |
| Dual-probe combo tester (thermal + electrical) | Correctly identifies moissanite |
| Professional gemological evaluation (loupe, refractometer, microscope) | Always correctly identifies moissanite |
Moissanite doesn’t contain the same chemical properties of diamond. However, it has a high thermal conductivity that may incorrectly register as a diamond when coming into contact with a thermal diamond tester. However, moissanite will not be able to pass other testing methods or professional evaluation.
Does VVS Moissanite Pass a Diamond Tester?
Yes, VVS moissanite passes a standard diamond tester. The VVS grade (Very Very Slightly Included) refers to the clarity of the stone, not its chemical composition — so the underlying silicon carbide structure and thermal conductivity are the same as any other moissanite. To a thermal tester, VVS moissanite and lower-clarity moissanite read identically as "diamond."
The same is true for moissanite-set chains, pendants, and rings. A VVS moissanite chain will pass a thermal diamond tester everywhere a single stone would, because every individual stone in the setting is still moissanite. This is part of why VVS moissanite is such a popular alternative to a diamond-set chain — the visual sparkle and the tester result both match what you would see with real diamonds, at a fraction of the price.
If you specifically want to verify that a chain or ring is genuine VVS moissanite (and not a lower-grade simulant like cubic zirconia), use a combination tester. Cubic zirconia will fail the thermal test entirely, while genuine moissanite will pass the thermal test but fail the electrical test — confirming it is the real product.
How to Tell If Your Stone Is Moissanite or Diamond
If you suspect a stone might be moissanite rather than diamond, here is a 5-step verification process you can do (some at home, some with a jeweler):
If you bought your moissanite from a reputable seller, you should also have received a certificate of authenticity. This is the cleanest proof of what you actually own, and it documents the grade, carat, and origin of the stone.
What Other Stones Pass a Diamond Tester?
Moissanite is by far the most common stone that passes a standard diamond tester, but it is not the only one. Here is a quick rundown of what does and does not pass:
| Stone | Standard Tester Result | Notes |
|---|---|---|
| Lab-grown diamonds | Pass every test | Because they ARE real diamonds. Same chemical composition, same thermal and electrical properties. |
| Moissanite | Passes thermal testers | Fails electrical conductivity testers. |
| White sapphire | Fails most thermal testers (lower conductivity) | Occasionally produces ambiguous readings on older units. |
| Cubic zirconia (CZ) | Fails immediately on thermal testers | Very different thermal profile from diamond. |
| Glass, quartz, topaz | Fail every standard diamond test | Thermal, electrical, and visual. |
In short, when a single-probe diamond tester flags something as "diamond," there are only really two possibilities: a real diamond (natural or lab-grown) or moissanite. Everything else fails the basic test.
Final Thoughts & Recommendations
Can moissanite pass for diamond? Will moissanite pass the diamond tester? Under certain circumstances, moissanite can pass the diamond tester if it is testing for thermal conductivity. Can a diamond tester detect moissanite? Moissanite may also fool a diamond tester pen if the pen isn’t positioned correctly. Moissanite must be evaluated using other gemological tools and methods. It is important to note that moissanite and diamonds are different gemstones; they may at first look alike because they sparkle but exhibit dissimilar chemical, optical and physical properties. Getting your diamond or moissanite certified guarantees the purchase is what you have paid for--it also brings relief in knowing you have valued your item at a correct cost.
Frequently Asked Questions
Will anyone know my ring is moissanite?
Because moissanite is distinctively different from a diamond and exhibits unique optical properties with its high refractive index, it may not be mistaken for a diamond by the trained eye. MOissanite has a rainbow brilliance, making it uniquely stunning. Both stones exhibit the fire and sparkle, but moissanite has features a colorful light dispersion. For the untrained eye, at first glance, a moissanite may be mistaken for a diamond.
Do you get a certificate with moissanite?
Moissanite is graded for quality using the 4Cs grading scale developed by the Gemological Institute of America (GIA) using the same criteria as diamonds. The 4Cs include color, clarity, cut, and caratage. Moissanite may be accompanied by a certificate of authenticity relating these facts and signed by a jewelry professional, most notably a Graduate Gemologist (GG).
Can a diamond tester detect moissanite?
A standard single-probe diamond tester cannot detect moissanite — it will read moissanite as a diamond because both stones conduct heat at nearly the same rate. A dual-probe combination tester, which also measures electrical conductivity, can detect moissanite reliably. Moissanite conducts electricity; diamond does not. Most modern combo testers display a separate indicator for moissanite results.
Why do some moissanites pass and others fail?
Virtually all genuine moissanite passes a thermal diamond tester. If a stone you thought was moissanite fails the tester completely, it is more likely a cheaper diamond simulant being sold as moissanite, such as cubic zirconia. Real moissanite is consistent: silicon carbide always conducts heat at roughly the same rate, regardless of size, cut, or clarity grade.
Does fake moissanite pass a diamond tester?
No. "Fake moissanite" usually means cubic zirconia or glass being sold as moissanite, and both fail a standard diamond tester immediately. If a stone passes the thermal diamond test but fails an electrical conductivity test, it is genuine moissanite. If it fails both, it is a different simulant.
How does a diamond tester work on a moissanite chain?
A diamond tester works on each individual stone in a moissanite chain or pendant, not the chain as a whole. Place the probe tip directly on a stone, hold it flat, and the tester reads that single stone’s thermal conductivity.
Will a jeweler be able to tell my moissanite is not a diamond?
Yes. A trained jeweler with a 10x loupe can usually tell within seconds because moissanite is doubly refractive (lines and facet edges appear to double when viewed at the right angle) while diamond is singly refractive. They also have access to dual testers and refractometers.
