If you've ever typed "how do I know if a crystal is real" into Google, you've probably come across the same advice repeated on forums, TikTok, and across social media. Some of it sounds convincing. Some of it seems very scientific. And some of it feels like insider knowledge reserved for "true experts" only.
But most of it is wrong.
Below are the three most popular tests for checking crystal authenticity — and an explanation of why not one of them actually works.
1. The flame test
People claim you can easily verify authenticity using a lighter or an open flame: "If it melts, smokes black, or smells like plastic, it's a fake."
At first glance, it sounds logical. Hold a crystal to the flame — if it melts or smokes, it's fake. If it doesn't, it's real. But this logic breaks down for the following reasons.
Many crystal fakes are made from glass or other highly stable materials. Glass won't melt in a flame and won't give off a plastic smell, so you might easily conclude a crystal is genuine when it isn't.
On the other hand, many genuine crystals are coated with a protective layer of resin. This is especially true for pendants made from raw crystals or from more delicate minerals. The resin protects them and gives them durability. If you burn it off, the resin will indeed disappear — but the crystal beneath will be left exposed and vulnerable.
This happened to one of our customers. She tested a pendant she had just bought. The flame melted the protective resin — but underneath was a genuine crystal. Without its protective coating, it became more susceptible to damage, and she'll likely find it chips more easily or changes in texture over time.
Some crystals, such as selenite and celestite, are naturally delicate in their own right. Even without any resin coating, a flame can discolour, crack, or permanently damage them. Heating certain crystals can also pose the risk of a small explosion, particularly if microscopic water bubbles are trapped inside.
This test proves nothing — and often destroys a crystal that was perfectly genuine.
2. The scratch test
People say: "If it doesn't scratch glass, it's a fake."
Or: "If glass scratches it, it's a fake."
This idea comes from the Mohs hardness scale, which assigns minerals a rating from 1 to 10. Quartz — a very common crystal — has a hardness of 7. Ordinary glass rates around 5.5. Quartz should therefore scratch glass, while glass should not be able to scratch quartz.
That is true — for Quartz. But most crystals don't share the same hardness as quartz.
Fluorite has a hardness of 4. Calcite and celestite both sit at 3. Selenite is just 2. All of these are natural minerals — and all of them are softer than glass. That means they won't scratch glass, and if you rub glass against them, you will almost certainly damage the surface of the crystal. By this logic, you could wrongly "accuse" a genuine crystal of being a fake.
Some people use a knife for this test, where the damage can be even greater. You can scratch, chip, or create micro-fractures in a crystal that only become visible later. Even if a crystal "passes" the test, it's often damaged in the process.
Every mineral has its own hardness — which makes this test far from reliable.
3. The cold touch test
People say: "If it feels cold to the touch, it's a real crystal. If it feels warm, it's a fake."
This test is popular because it's simple and doesn't damage the crystal. It also sounds fairly logical. Crystals do often feel cooler than plastic, because they conduct heat differently.
But glass gives the same cool sensation. And many fakes are made from exactly that.
Temperature can also mislead very easily. If a crystal has been sitting in sunlight, in a warm room, or carried in a pocket, it will feel warm. If it's been placed by a draughty window, under air conditioning, or in a cool room, it will feel cold. Temperature has nothing to do with authenticity.
Crystals vary enormously from one another — some have smooth surfaces, others are raw, and others still are stabilised or protected with coatings. All of these factors influence the temperature you feel when you touch them.
If you're relying on temperature, you're guessing. Not testing.
So how do you actually avoid fakes?
These three tests don't work because each one tries to apply a single rule across many very different types of crystals. Such theories assume that all fakes are soft plastic and all genuine crystals are hard, cool, and uncoated.
But crystals are not all the same.
If you want to avoid fakes, the better approach is to research each mineral you're interested in before you buy. Ask the seller about its origin. Look for irregularities, natural colour variation, and texture. And buy from people who can actually answer those questions.
Don't destroy a crystal trying to prove it's real. There are better ways. And better sellers.
