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Moissanite is the stone that’s most similar to diamond in terms of its look and other key characteristics. While your friends may not be able to tell your Moissanite from a diamond, can trained professionals with some common tools of the trade?

Will Moissanite Pass a Diamond Tester? Moissanite will often be misidentified as diamond by basic diamond testers because they only test heat conductivity and Moissanite is very similar to diamonds in that area. Testing electrical conductivity is a more certain way to distinguish the two stones. Some multi-testers can measure both.

Will your local jeweler or pawn shop have the right kind of tester on hand to positively distinguish Moissanite from Diamond? In this article, I’ll share the tools that can accurately distinguish the two stones—and those that simply can’t.

What Makes Moissanite Unique?

Moissanite is a natural material with a background that’s almost too incredible and mysterious to believe. The stone was first discovered in tiny fragments at the site of a meteor impact in an Arizona desert. Most natural Moissanite is still found at meteorite impact sites around the world—so it has obviously traveled quite some distance through space before making impact with earth. Moissanite is made of Silicon Carbide (SiC). There is evidence that the SiC grains that comprise most natural Moissanite “originates around carbon-rich Asymptotic giant branch stars. SiC is commonly found around these stars as deduced from their infrared spectra.” The French scientist that discovered it thought the specimen was diamond for many years. Eventually, it’s true nature was discovered. Synthetic production started soon after.

Moissanite is incredibly hard, in fact, the only stone that’s known to be harder is diamond. That made synthetic Moissanite a great (and more affordable) choice for many industrial applications (like industrial abrasives). Moissanite has been used in jewelry since the 1990s, but today’s quality standards are much younger. Over the past ten years or so, technology has advanced to the point that synthetic Moissanite can be truly colorless. This makes it a great diamond alternative for many jewelry applications. It has a beautiful diamond-like appearance and durability, but costs 90% less!

Moissanite has other characteristics that are worth noting. It conducts heat very similarly to diamond—but conducts electricity MUCH BETTER than diamond can. The difference in electrical conductivity is a more certain differentiator that can positively distinguish between Moissanite and Diamond.

The Value, and Limitations, of a Diamond Tester

The Diamond Tester has become standard gemological equipment. Your basic diamond tester only tests one thing—thermal conductivity, which means it can distinguish diamonds and moissanite from other stones, like Cubic Zirconia (CZ), but it typically CAN’T tell Moissanite and Diamonds apart (it registers both as diamond).

Heat conductivity isn’t exactly the same for Moissanite and Diamond, but it’s really close. Many diamond testers can’t perceive the small difference, others are fooled because they aren’t calibrated properly to pick up the slight difference in conductivity. Even with their limitations, Diamond Testers are still valuable tools for jewelers and gemologists, they just can’t be trusted to tell the full story. In order to differentiate diamonds from Moissanite, a second tool (or functionality) is required.

Moissanite is (very slightly) electrically conductive—so slightly, that you need specialized equipment to detect it. A device called a Moissanite Tester has been designed for that very purpose. Moissanite testers only measure electrical conductivity—so they can easily distinguish between diamonds and Moissanite because diamonds are not electrically conductive.

Moissanite isn’t unique as a stone that’s electrically conductive, there are a number of gemstones that share that quality, but, again, diamonds are not one of them. Having access to BOTH a Diamond Tester and a Moissanite Tester allows you to positively identify whether a particular stone is a diamond, Moissanite, or something else more consistently. If your Diamond Tester identifies a given stone as “diamond,” you’ll know that it’s either diamond or Moissanite. As a subsequent test, If your Moissanite Tester indicates that the stone is ‘Moissanite,’ you’ll have a positive identification (that it is, in fact, Moissy)—otherwise, you can be certain it’s diamond.

Again, because of the limitations of the standard Diamond Tester, you’ll also need to purchase a stand-alone Moissanite tester in order to get conclusive results.

The Advantages of a Multi-Tester for Identifying Moissanite

Multi-testers are the combination of a diamond tester and moissanite tester in one compact tool. They measure BOTH thermal AND electrical conductivity. Multi-testers are obviously more expensive, but there’s a convenience to only needing to have one tool on hand in order to get the information that you need on a particular stone.

As with all the tools that I’ve referenced so far, quality matters A LOT! You’ll find a wide range of instruments being offered. Accuracy and durability are obviously important considerations. The cheapest one isn’t always the one you want. On the flip side, the most expensive one isn’t always the best route either. Reviews from past buyers can be a huge help a lot. As you read those, you’ll be able to quickly weed out the models that won’t be a good fit.

Basic diamond testers start at about $15. A quality tester runs about $120. Here’s a link to the diamond tester that offers the best overall value. It’s available on Amazon and is accurate, small, and durable.

Moissanite only testers will likely cost a little more than $100. A multi-tester is probably a better way to go, overall, but this is the standalone Moissanite tester that I like best.

Most multi-testers start at about $250. Check out my favorite multi-tester on Amazon. It comes from a manufacturer with a solid reputation and offers the biggest bang for your buck, in my opinion.

Other Options for Testing Your Moissanite

You don’t always have to have a Diamond Tester and a Moissanite Tester (or a Multi Tester) in hand in order to differentiate diamond and Moissanite. There are a few simple tell-tale signs that you can look for to help you spot Moissanite when you don’t have your instruments with you.

You can look for signs of ‘double refraction’ through a jeweler’s loupe, for example, if you know what to look for. Double refraction happens when light is slowed, bent, and spit in two as it travels through certain stones. You only notice this characteristic when a trained eye views the stone under at least 10X magnification from the right angles (knowing what to look for). Double refraction makes the lines between facets look blurred and multiplied. When you look through a similar diamond, for example, from the same angle, you’d see one clean, sharp, line on the other side instead of multiple blurred lines.

Easy Ways to Tell if a Stone is Moissanite or Diamond

Moissanite is intentionally cut so that it isn’t doubly refractive through the top (the table) of the stone. When you look through the table of a Moissanite stone, you’re viewing a singly refractive stone (from that angle). In order to witness the effect, you have to look just a little lower, through the crown-facet (the angled surface around the top portion of the ring … just below the flat table of the stone).An illustration of the angles as which Moissanite is singly refractive and doubly refractive

Moissanite isn’t alone in this interesting characteristic. The following stones are ALSO double refractive:

  • Sapphire
  • Zircon
  • Peridot
  • Tourmaline

Critics of Moissanite (usually those selling diamonds or Cubic Zirconia), often talk about the double refractive properties of Moissanite as a bad thing. This is because double refraction is, at least partially, responsible for the abundance of colorful sparkle that Moissanite is known to produce.

The saying, ‘one man’s trash is another man’s treasure’ comes to mind, because many faithful fans of Moissanite LOVE the fire (the colorful sparkle effect) that Moissanite produces. My mother is one that can NEVER get enough sparkle. Any characteristic that causes more sparkle is something she’s a big fan of! Double refraction doesn’t impact or diminish the beauty and charm of Moissanite in any way.

Another way to distinguish Moissanite from diamonds, without costly equipment, is by observing the amount of ‘fire’ that each stone has. In gemology, the term ‘fire’ refers to the colorful sparkles (or flashes) that you observe as you move the ring under light. A ring with a lot of colorful sparkles is said to be ‘fiery’. Diamonds have fiery properties, but they aren’t nearly as fiery as Moissanite.

Moissanites refractive index is considerably higher than diamond’s which is why Moissanite is more fiery.

Refractive Index

  • Diamond: 2.42
  • Moissanite: 2.63

The fiery nature of Moissanite is best observed with larger stones, as they’re being exposed to natural lighting. Some people (again, like my mother) LOVE the added colorful sparkle, but others aren’t fans because they think it makes their diamond look a little different than diamond might under certain lighting conditions. Some people refer to the fiery nature of stones as the ‘disco ball effect’ or the ‘rainbow effect.’ Identifying Moissanite, based on the amount of fire displayed by a given stone, becomes much more difficult as the stone size decreases.

One other, fairly low-tech, way to distinguish diamonds from Moissanite, is by comparing weight and size measurements.

The size of diamonds is communicated in terms of ‘Carats,’ which is actually a weight measurement. One-carat equals 200 milligrams (mm). Moissanite weighs 15% to 18% less than a diamond of equal size. This difference in stone density is why the size of Moissanite is typically communicated in mm rather than carats. If both were communicated in carats, then a 1 carat Moissanite would always be physically larger than a 1-carat diamond, for example.

Based on all of this, if you weigh and measure a diamond or Moissanite, you should be able to clearly distinguish the two.

In Summary

Standard diamond testers can’t be trusted to accurately, and reliably, identify Moissanite. You’ll need to add a separate Moissanite tester, or get a multi-tool that tests both thermal and electrical conductivity, in order to get a dependable identification. If all else fails, there are also several low-tech ways that you can distinguish diamonds from Moissanite.

Related Posts:

6 Ways You Can Tell a Lab Grown Diamond From a Natural One

Is Moissanite Good for an Engagement Ring? | 8 Useful Facts

It’s Pretty, But Is Moissanite a Good Diamond Alternative?

 

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