Do you need to know how to test a crystal to make sure it’s real fluorite?
You can tell if a fluorite crystal is real with some easy tests at home, such as putting lemon juice on it to make sure it doesn’t fizz, shining a UV light on it to see if it glows, and measuring its weight in water.
Perhaps you want to test if a crystal is fake. Even though fluorite isn’t a very rare or expensive crystal, there are still imitations on the market, which are usually glass, plastic, or etched quartz.
Or perhaps you’ve found a a crystal and suspect it’s fluorite, but you want to make sure.
Keep reading for 14 easy ways to do this with step-by-step instructions, so you can use a process of elimination to make an informed decision.
By the end of this post, you’ll have 14 ways to tell if a fluorite crystal is real, fake, or another crystal.
Has a specific gravity of 3.2
Fluorite has a specific gravity of 3.17 to 3.7, depending on what’s in the crystal.
A fairly accurate way to tell if fluorite is real crystal and not glass is to measure its specific gravity. Don’t be scared – I’ll show you how!
To get an object’s specific gravity, we measure how much space it takes when we drop it in water.
The specific gravity of most fluorite is 3.2 when rounded off, which can be measured using a digital scale that shows at least two decimal points.
Here are the steps to calculate the specific gravity of a fluorite crystal:
- Weigh a container and write down the weight up to two decimal places. Make sure the container is large enough to hold water and the fluorite you are testing.
- Add water to the container and take this measurement, again with two decimal places.
- Put the crystal in the water. Now write down this measurement up to two decimal places.
- Subtract the weight of the empty container from the weight of the water-filled container and the water and crystal weight. You now have the true weights of the water and the water and crystal together.
- Divide the true weight of the crystal and water weight by the true weight of the water-only weight. This gives you the crystal’s specific gravity.
- If the specific gravity is 3.2 when rounded off, then you probably have a real fluorite crystal. Keep in mind that if it has a lot of rare earth minerals in it, its specific gravity could even go as high as 3.7. So anything from 3.17 to 3.7 is appropriate.
This method confirms that the piece is real crystal and not glass, which is lighter than crystal. And if the specific gravity is between 3.17 and 3.7, there’s a good chance it’s fluorite – that is unless you happen to have another crystal with the same specific gravity.
If you want to be sure it’s fluorite, I recommend using a combination of methods described in this blog post.
Comes in different colors
Natural fluorite occurs in a variety of colors, like purple, green, yellow, blue, pink, and clear. It can also have many colors in a single crystal, and have a banded or striped appearance.
Sometimes crystals are treated to artificially enhance or change their color. They may be treated with heat or irradiation, or given a coating of a thin layer of a different mineral or pigment. This doesn’t make the crystal a fake necessarily, it could just mean that you have a real fluorite crystal that’s been treated to look different.
Real fluorite usually has a consistent color, without major variations or changes in shade. It can also be transparent or translucent, letting light pass through it.
Shines under UV light
Some varieties of fluorite shine under UV light. This is called fluorescence.
Not all natural fluorite crystals are fluorescent and not all fluorescent crystals are real. But testing for fluorescence is one way that helps you establish the authenticity of a fluorite crystal.
Here’s how to use fluorescence to test if a fluorite crystal is real or not:
- Get a UV light – either online (like this one from Amazon) or at a hardware store.
- Wait for nightfall, then turn off the lights and shine the UV light on the crystal in question. If it’s real fluorite it probably has impurities or defects in it that glow or fluoresce in the UV light.
Real fluorite crystals can fluoresce in different colors, like blue, green, yellow, purple, or red. And the fluorescence ranges from a faint glow to a bright and intense light. The color and intensity of the fluorescence all depend on the impurities or defects in the crystal.
Fake fluorite usually doesn’t fluoresce under UV light, or it may shine a different color or intensity of fluorescence than natural fluorite.
Does not release oils in the sun
Though fake fluorite it not very common, some unethical dealers etch fake fluorite out of quartz, then oil the crystal to make it look more like fluorite.
If you think you have a fake shiny fluorite, put it out in the hot sun and leave it there for a few hours. The heat will bring out any oils and if there is oil present, you’ll see a film or droplets on the crystal.
Oil doesn’t tell you beyond a doubt if a crystal is fake. But it does tell you that it’s been oiled and you now have good reason to investigate further…
Has perfect cleavage planes where it breaks under pressure
A cleavage plane is a line of weakness where a crystal breaks under pressure.
One trait of real fluorite is its four perfect cleavage planes. In fact, we can predict exactly where and how a real fluorite crystal will break, and fluorite always makes four clean, straight breaks under pressure. Fake fluorite does not have this trait.
Here’s how to test fluorite’s cleavage planes:
- Get a sharp object, like a metal knife.
- Carefully examine the crystal to see if you can find its cleavage planes. Look for flat, smooth surfaces or lines/markings that run parallel to each other and cross at right angles (90°).
- When you think you’ve found a cleavage plane, put the crystal on a flat surface and hold it in place. Now gently apply pressure with the tip of the sharp object along the potential cleavage plane.
- If the crystal breaks cleanly and smoothly along this plane, it’s a good indication that it’s natural fluorite.
- If the crystal does not break cleanly along each cleavage plane that you test, it could be a fake or another type of crystal.
Even though cleavage planes can help us identify fluorite’s authenticity, it should be used with other tests to be sure.
All crystals can be measured on the Mohs scale to determine how hard or soft the crystal is.
Fluorite is a 4 out of 10 on the Mohs scale, which is quite low, but it’s still higher and harder than copper at 3.5.
This gives us one easy way to test if a fluorite crystal is real or not:
If the crystal can scratch a copper penny and cannot be scratched by the same penny, there’s a chance it’s fluorite.
Can be scratched by steel
Real fluorite is softer than steel.
To test if fluorite is real, scratch it with a piece of steel (a knife, watch casing, or steel file).
If the steel scratches the crystal’s surface, then it’s probably real fluorite. You may need to look at the crystal through a magnifying glass to see if there is a mark or not.
Does not fizz in weak acids
Fluorite does not fizz or bubble in weak acids, like hydrochloric acid, lemon juice, or vinegar, but fake fluorite won’t fizz in acid either. However, if you pour acid over the crystal and it fizzes, it’s probably another crystal, like calcite.
Read this article if you need to know how to tell the difference between fluorite and calcite.
Here’s how to do an acid test on a potential fluorite crystal:
- Get some weak acid, like hydrochloric acid, vinegar, or lemon juice.
- Pour a little acid onto a non-visible area of the crystal, such as on the underside of the crystal or on a rough surface.
- Watch how the crystal reacts to the acid: Fluorite does not react with weak acids. If the crystal fizzes or bubbles it’s probably not fluorite but another crystal.
- Rinse the acid off the crystal with clean water to prevent damage and stains.
Note that the acid test should be done with caution because acids can damage or mark some crystals.
Makes different colors under polarized light
Real fluorite has a special property that shows many different colors under polarized light. This means that you can use a polarization test to see if the crystal you have is real fluorite or not.
Here’s how to perform a polarization test on fluorite:
- Get a polarizing filter or a pair of polarized sunglasses and a flashlight.
- Put the crystal on a flat surface and shine the light through the filter onto the crystal.
- Hold the filter close to the crystal and turn it slowly.
- Watch the crystal through the filter as you turn it.
- Fluorite shows different colors and patterns under a polarizing filter. If the crystal stays one color or shows no color at all, it’s not fluorite.
Can be tumbled, for a short while
It’s much easier to tell if raw rough fluorite is real or not. But what about the smooth, tumbled crystals that are more likely to be fakes?
Fluorite is strong enough to be tumbled, but not for as long as you can tumble other harder crystals.
Tumbling takes a raw crystal from the ground and makes it smooth, round or oval-shaped, and shiny.
This is done by putting the crystal into a machine that rolls the crystal around with rocks or other crystals. As the rocks and crystals roll around, a crystal’s rough edges are removed. But put glass in a tumbler and it shatters.
If you want to do your own tumble test to see if you have real crystal or a glass fake, use this hobby rock tumbler kit to tumble the piece for a few minutes or hours and see if it survives.
If it does, it’s probably real crystal. If it breaks up into small pieces or shatters, it’s most likely glass.
Makes a high-pitched sound when tapped
Fluorite crystal makes a clear, high-pitched sound when tapped with a metal spoon or piece of quartz. This sounds a lot like the sound when you tap a wine glass or bell with a steel knife. If the crystal makes no sound or a dull sound, it’s not likely to be fluorite.
Here’s how to do a sound test on fluorite:
- Get a hard object like a metal spoon or a piece of quartz.
- Hold the crystal lightly between the tips of your fingers in one hand and the hard object in the other hand.
- Gently tap the crystal with the hard object, using a light to moderate force.
- Listen to the sound that the crystal makes.
A clear, high-pitched sound is probably fluorite, but a dull, thudding sound is not. It’s important to note that the sound test is not foolproof but it can help you identify a fake.
Is about the same price, no matter where you buy it
The cost of fluorite depends on the quality, color, and size of the crystal, as well as how many people want to buy it and how many crystals are available.
Also, there are a limited number of fluorite suppliers. These suppliers sell crystals to retailers for about the same price, who sell them on to you and me.
Retailers must sell the crystals for a certain amount to make a profit, which is more than what they paid to their supplier.
So if you find fluorite that’s on sale for a price that’s too good to be true (much cheaper than other sellers), it’s probably fake crystal.
Here is a table with the average price ranges of fluorite per carat:
|Quality||Price Range (USD)|
|Low quality||< $1 per carat|
|Medium quality||$1-$10 per carat|
|High quality||$10-$50 per carat|
|Exceptional quality||$50+ per carat|
Comes from a trustworthy seller
If you buy fluorite from a seller that you know you can trust, and that seller tells you the crystal is real, then it probably is.
Some things you can do to make sure the seller can be trusted is:
- Do some research on the seller, to look for bad reviews or complaints that other people have made. You can also speak to others or join Facebook groups and ask for recommendations.
- Check the seller’s website to see what information they give and if they look authentic.
- Ask the seller to provide proof on where they got the fluorite from.
- Buy fluorite jewelry that is certified by the Gemological Institute of America (GIA) or the gem certification body in your country.
Can be confirmed by a professional
If you must know if a stone is real fluorite or not, and none of the above methods have given you a definitive answer, then ask a professional crystal dealer, lapidist, or appraiser to take a look at the crystal.
A professional will have the tools, knowledge, and experience to give you a better idea if a crystal is real or not.