Moissanite will pass for a diamond when using a regular diamond tester. These testers rely on thermal conductivity measurements. As moissanite and diamond have similar conductivity, they won't be able to tell them apart. So, with a regular tester, moissanite registers as a diamond.
Moissanite is gaining popularity as an eco-friendly and ethical alternative to natural diamonds. The brilliance and durability of moissanite make it an attractive choice for jewelry. It is an ideal gemstone for engagement rings and wedding bands.
Although moissanite is a complete gemstone in its own right, it is often compared to a diamond. It has a striking resemblance to a diamond, making it a great diamond alternative.
Both stones are also similar in their hardness and thermal conductivity. So, most diamond testers cannot differentiate between them.
In this post, we’ll see why standard diamond testers can't accurately distinguish between the two gemstones. We will also see what tools you can use to differentiate diamonds and moissanite.
What is Moissanite?
Moissanite is a natural gemstone with an origin story that is out of this world, quite literally. The stone was discovered by the scientist Henry Moissan in a meteor crater in the Arizona desert. Moissanite is composed of Silicon Carbide crystals.
Most natural moissanite is still found in meteor impact sites. Since its discovery, scientists have been able to replicate it under lab conditions. The synthetic moissanite is chemically and physically identical to the natural gemstone. It also has the same optical property.
With a hardness rating of 9.25-9.5 on Moh's hardness scale, it comes close to a diamond with a rating of 10. In other words, a moissanite is as durable as a diamond and will last a lifetime without needing special care.
The physical appearance of moissanite also matches closely with that of a diamond. It is difficult to differentiate between a moissanite and a diamond with the naked eye. And it is especially difficult without the two stones sitting next to each other.
Despite its brilliance, durability, and fire, moissanite can cost up to 19% less than a diamond. As it is lab-synthesized, it is also more eco-friendly and a conflict-free gemstone, increasing its appeal as a stone of choice for jewelry.
How does a diamond tester work?
Basic diamond testers tests the thermal conductivity of the gemstones. These are also called thermal conductivity pen testers. The thermal conductivity of natural diamonds is much different from a synthetic diamond and other diamond simulants. Hence, a diamond tester can tell them apart.
Most diamond testers use a heated metal tip to send heat to the surface that they touch, such as a gemstone. The instrument is designed to detect the heat transfer rate from this heated metal tip into the surface it touches.
Different gemstones have different chemical characteristics and heat conductivity. A diamond tester uses this slight difference in conductivity to tell the stones apart.
A diamond can conduct heat, but at a very slow rate that is not matched by other stones like cubic zirconia that share a similar appearance. Hence, basic diamond testers can distinguish between real and lab-made diamonds with ease.
Things get tricky if a gemstone that looks like a diamond has a near-identical thermal conductivity. One such gemstone is moissanite.
Does Moissanite pass basic diamond testers?
In a word, yes. Moissanite conducts heat similarly to a diamond. So, if you use your regular diamond tester on a moissanite, it will be registered as a diamond. Although a diamond tester can't differentiate moissanite from a diamond, it is greatly useful to a gemologist.
The heat conductivity of both stones is very close but not identical. However, regular diamond testers won't be able to register these minor differences. Even the most sophisticated diamond testers need to be more sensitive to spot this difference.
Suppose a tester does pick up on the small conductivity difference; it needs to be calibrated properly to perceive it. Unfortunately, most testers are not; hence, they always register moissanite as a real diamond.
Is there a Moissanite tester?
A special moissanite tester is available that can differentiate between a diamond and moissanite. These testers test electrical conductivity rather than thermal conductivity.
As moissanites have slight electric conductivity, they test positive. Diamonds have no electrical conductivity and test negative using this tester.
The drawback of Moissanite testers
Several other gemstones also have electrical conductivity, just like moissanite. Hence, the electrical conductivity testers won't be able to tell moissanite from cubic zirconia apart.
Hence, an electrical conductivity tester alone is not quite useful. To overcome this problem, today's diamond testers use multi-tester technology.
These multi-testers are testers that can measure thermal and electrical conductivity. A multi-tester can easily differentiate between a diamond, moissanite, and any other gemstone.
How to distinguish diamonds from Moissanite using a diamond tester?
Here is how you can use both a diamond tester and a moissanite tester to check whether your stone is a diamond or a moissanite:
- Use the diamond tester to test the stone.
- If it registers as a diamond, you know it can be either a diamond or a moissanite.
Next, check both stones with a moissanite tester. If it tests for moissanite, you can be certain it is a moissanite. Otherwise, it is certainly a diamond.
Despite the existence of these multi-testers, it can be difficult to authenticate a diamond at times. There aren't any at-home methods or tests that can give you 100% reliable results.
If you are unsure about the authenticity of your diamond or moissanite using diamond tester, you should take it to a trained jeweler. Sophisticated instruments in a gemological lab can get the job done.
Other options for testing your Moissanite
If placed side-by-side, it would be impossible to differentiate a moissanite from a diamond. However, other options exist besides a diamond tester to test your moissanite.
A specialist can tell the difference between a moissanite and a diamond by observing the stones under a magnifying glass.
The 'disco ball' effect
A moissanite has a greater brilliance than a diamond. In other words, moissanite sparkles more than a similar-sized diamond. Moissanite creates almost a 'disco-ball' effect when hit by light. A jeweler's loupe can be used to see this effect.
The reason for this effect is moissanites refractive index being higher. As moissanite is optically denser than a diamond, light bends more when it enters the moissanite crystal structure from the air.
- Refractive index (RI) of diamond: 2.42
- RI of moissanite: 2.67
Moissanite gives double refraction, while a diamond gives single refraction when light refracts. It means that two light rays emerge when a single beam of light enters a moissanite through the crown.