Does Moissanite Pass Diamond Tester? The Surprising Truth Behind the “Beep”
Curious if your stone is the real deal? We answer the trending question: “Does moissanite pass diamond tester?” Learn why basic thermal testers often get it wrong, the science behind the beep, and how to accurately distinguish the two.
The Dinner Party Test
Imagine this: You are at a dinner party, wearing your stunning new engagement ring. A friend, perhaps a bit skeptical or just curious, pulls out a small handheld device—a “Diamond Tester”—and asks to check your stone. You hold your breath. The tip touches the gem, and suddenly… BEEP! The red light flashes. It says “Diamond.”
But wait—you know it’s a Moissanite.
This scenario leads to one of the most frequently asked questions in the jewelry world: Does moissanite pass diamond tester?
The short answer is YES, in many cases, it does. But the full answer is a bit more complicated and fascinating. Let’s dive into the science behind the sparkle.
Why Does Moissanite Pass a Standard Diamond Tester?
To understand why moissanite “fools” the machine, you have to understand how the machine works.
Most inexpensive diamond testers (the ones you can buy on Amazon for $15) work by measuring Thermal Conductivity (how fast heat moves through an object).
Diamonds are incredible conductors of heat. That’s why they feel cold to the touch. When the tester tip heats up and touches the diamond, the stone pulls the heat away instantly. The machine detects this rapid heat loss and beeps “Diamond.”
Cubic Zirconia (CZ), glass, and plastic are insulators. They trap heat. The tester detects this resistance and stays silent.
Here is the catch: Moissanite (Silicon Carbide) is also an extremely effective conductor of heat. Its thermal properties are so similar to a diamond’s that a basic thermal tester cannot tell the difference. To a standard heat probe, a Moissanite and a Diamond look exactly the same—they both pull heat away rapidly.
The “False Positive” Example
Let’s look at a real-world example. John buys a vintage ring at an estate sale. The seller uses a standard “Diamond Selector II” pen. He touches the stone, it beeps loudly, and John buys it thinking he scored a massive natural diamond. Later, he takes it to a professional jeweler who uses a microscope. The jeweler spots the tell-tale “double refraction” of moissanite.
John’s tester wasn’t broken; it was just measuring the wrong thing. It proved the stone wasn’t glass or CZ, but it couldn’t prove it was a diamond.
How to Actually Tell Them Apart (The Electrical Test)
If basic testers fail, how do gemologists distinguish them?
They use a more advanced device called a Multi-Tester (checking both heat and electricity). While Moissanite and Diamond conduct heat similarly, they conduct electricity very differently.
Diamonds (mostly) do not conduct electricity.
Moissanite contains small amounts of silicon which makes it slightly electrically conductive.
A specialized Multi-Tester sends a tiny electrical current through the stone. If the current passes through, the machine knows it’s Moissanite. If the current is blocked, it confirms it’s a Diamond.
Does It Matter if It Passes?
So, does moissanite pass diamond tester? Yes, it often does on standard equipment. This is actually a testament to the quality of Moissanite. It shares so many physical properties with diamonds—hardness (9.25 vs 10), brilliance, and thermal conductivity—that it takes specialized equipment to tell them apart.
However, we believe you shouldn’t buy Moissanite just because it can “pass” as a diamond. You should buy it because it is a stunning gemstone in its own right—with more fire (rainbow sparkle) than a diamond, extreme durability, and a completely conflict-free origin, all at a fraction of the price.
Next time someone asks, “Is that real?” you can smile. Whether it passes a thermal test or not, the sparkle on your finger is very real.
Ready to find a gem that rivals the best?
