How to Tell if a Diamond is Real With a Flashlight?

Last Updated on May, 2024

They say a diamond is a girl’s best friend. But what use is a best friend that isn’t REAL! Natural diamonds have a beautiful shine, and fake diamonds often don’t look very different from real ones. 

A diamond tester can surely tell you if the diamond is real, but can it be done with a flashlight?

If so, how to tell if a diamond is real with a flashlight? 

Quick Summary

The real diamond will shine and glimmer when a flashlight is shone on it, while a fake diamond will not reflect light in the same way.

The shine and glimmer of a real diamond are caused by the reflection of light from the surface of a perfectly cut diamond.

The real diamond will emit a sparkle of gray and white light known as ‘brilliance’, along with flashes of color called ‘fire’ when a flashlight is shone on it.

How to Use a Flashlight to Check if a Diamond is Real?

 a flashlight on the table and a human holding a Diamond

You CAN use a flashlight to tell if a diamond is real. This is one of the easiest means of checking for a real diamond.

Real diamonds have a certain shine to them that fake diamonds do not. Fake diamonds don’t behave the same way when a flashlight is shown on them. Real diamonds will have more of a shine and glimmer when a flashlight is shone on them. 

To check if the diamond in your hands is a fake diamond or a real diamond, shine the flashlight on the diamond. If the diamond is real, there will be a shine and glimmer, much like a disco ball of rainbow colors. 

This shine and glimmer will not be present if you shine a flashlight onto a fake diamond. 

Fake diamonds will not reflect light the same way as real diamonds. A real diamond will have the ability to reflect light much BETTER! This is why real diamonds glimmer and shine when a light source such as a flashlight is shone on them. 

This is how you can use a flashlight to tell between a fake diamond and a real diamond. 

What You Need to Test a Diamond?

Diamond on the table

In most cases, when checking for the validity of a real or fake diamond, people tend to rely on diamond testers to validate. However, you may need to get your hands on a diamond tester, in which case a flashlight can tell if a diamond is real. 

All you need is a flashlight with a good brightness level. 

Lab-created and mined diamonds have the features necessary to prove positive in a test with a flashlight. 

Mined diamonds have the same structure and shine as lab-created diamonds; both are considered real diamonds. 

In actuality, though there are many ways you can test the validity of a diamond, the easiest way to check if a diamond is real is by simply getting your flashlight and shining the light on the diamond. 

The Process of Checking if Diamond is Real with a Flashlight

Not all diamonds reflect light the same way. Both lab-grown diamonds and diamonds that are mined from the EARTH have the ability to reflect light better. This is the premise upon which the validity of that diamond ring on your hand can be tested. 

The process involves getting your hands on a good flashlight. Once you have a flashlight, you need to shine the light on the diamond. If the diamond is real, you will notice that the diamond SHINES! The shining is caused by the reflection of light from the surface of the perfectly cut diamond. 

This is how to tell if a diamond is real with a flashlight. If you would like to, you can use a magnifying glass to look at the shine up close to get a better idea of whether it is a good shine and glow. 

A real diamond is internally flawless. Any local diamond expert will tell you that the structure of a real diamond and a fake diamond is different. This is why they behave differently when a light source is shone on them. 

How to Tell if Diamond is Real With Flashlight?

Diamonds on the table

Diamonds that are real sparkle. Though fake diamonds also sparkle, they don’t behave the same way when a strong light is cast on them, such as a flashlight.

You may see a blue glow or an array of colors of a rainbow when a flashlight is shone on a real diamond. The rainbow colors are a telltale sign that the diamond is real. 

No reputable jeweler will knowingly sell you fake diamonds and put their reputation in jeopardy. However, you should do a test in the store to check if it is real. If you have a handy pocket flashlight with you, you can easily check the validity of any diamond, anywhere. 

Any real diamond, such as an engagement ring, will emit a sparkle of gray and white light known as ‘brilliance.’ The flashes of color that you may see are called ‘fire.’

Hence, when you shine a flashlight on a real diamond, you will see an array of brilliance and fire.

When proposing, you don’t want to find yourself harassed by your fiance due to the diamond being fake. Hence, when it comes to engagement rings, it is particularly best if you check the diamond, at least if not anything else with a flashlight – for brilliance and fire. 

Some gems like white sapphire, topaz, and white zircon resemble diamonds and act the same way to light. 

Synthetic diamonds have the same structure as diamonds mined from the EARTH, hence will successfully pass the sparkle test (with a flashlight.)

Look for the sparkle of light and colored light that should illuminate the surface of the diamond. Only diamonds that are real will do this when a flashlight is shone on them.

If you can, keep the stone upside down on the flashlight lens. This will help you better observe the spectrum of light that passes through and check for rainbow colors.

Do Real Diamonds Sparkle in the Light?

Sparkling Diamonds on the table

Yes, real diamonds do sparkle in the light. This is why you can use a flashlight to test the validity of a diamond. 

Though diamonds that are fake also sparkle in the presence of light, the sparkle of a real diamond is very different from that of a diamond that is fake. 

You will see an array of rainbow colors, or even gray and white light, which isn’t visible when you shine a light on a diamond that is not real. 

Do Real Diamonds Shine Without Light?

Diamonds only sparkle in the presence of light. Hence in the dark, real or fake, diamonds will not shine. 

Unless, of course, you are using a black light or a UV light, in which case, the diamond will glow. 

However, real or fake diamonds will not shine in the dark. That is not one of the properties of this stone.

Other Tests to See if Diamond is Real with a Flashlight

Apart from the fact that you can use a flashlight to test the validity of a diamond, there are other tests that you can rely on.

You can use a BLACK LIGHT to check the validity of a diamond. A black light will make the diamond shine hints of yellow, green, or gray when shone on a diamond that is REAL!

You can also use the scratch test to see whether a diamond is real. Scratch the surface of a mirror with the diamond. If the mirror is damaged, then the diamond is REAL!

UV light or a black light test is yet another thing that can be used to check the validity of a diamond. UV light will cause the light to glow in the dark. Real diamonds will glow in the dark in the presence of UV light. Here’s a list of top UV flashlight picks.

You can also use the DOT TEST to check if the diamond is real. This is similar to the newspaper test when you use letters in a newspaper instead of a dot. Place a small dot on white paper and keep the diamond on top.

If you can see the dot through the diamond, even if blurry, the diamond is fake. With a real diamond, the dot will disappear.

This test does not work with loose diamonds, though you can try this on a large enough loose diamond. 

For a loose stone, you can try the water test. That being the case, the problem with the water test is that fake diamonds do float in water, which is the test.

However, not all fake diamonds float in water. Hence, there are more reliable tests than this one.

a human using a UV flashlight to the diamond

You can also probe test and fog test a diamond for validity. The fog test is quite popular; you may have seen people do this. All you have to do is breathe on the diamond with an exhalation of air.

This will cause a buildup of fog on the diamond, which will disappear very fast if the diamond is real. If the fog doesn’t disappear, it is more likely that the diamond is fake. 

If you can get your hands on a thermal conductivity probe, you can use the probe to check the thermal conductivity of the stone. The thermal conductivity of real stones is different from that of fake stones. 

Much like the probe test, the heat test relies on a copper heat probe which also checks the thermal conductivity of the stone. 

Though harder to master, a magnifying glass test can also tell you if a diamond is real. Here, you have to use a magnifying glass to check for imperfections in the stone. The imperfections will tell you that the diamond is REAL. Real diamonds have imperfections!

Most diamonds must be tested to check their validity, as it is difficult to tell if a diamond is real or fake with the naked eye. Hence, inspect diamonds before purchase, which is always the wiser option. An electrical conductivity test will tell you if you have a low-quality diamond on your hands. 

The optical properties of fake and real diamonds are different, which is what is relied upon to test diamonds with flashlights!

Use of Flashlight in Testing Diamonds

flashlight and Diamond

Compared to all these ways to test the validity of a diamond, using a flashlight has to be the simplest and easiest. 

All you need to do is shine a flashlight on the diamond or place the diamond on the lens of the flashlight. By observing the light that is emitted and reflected off the diamond, you will be able to validate to a great degree of accuracy with regards to whether the diamond is real or not. 

Using a flashlight to test the validity of a diamond is handy! If you have a flashlight at home, you can test diamonds at home. 

Ideally, you should test a diamond’s validity before purchasing. Hence, nobody will look at you weirdly if you take a flashlight with you next time you go diamond shopping. 

Having a flashlight with you to test the validity of a diamond becomes one of the few things that you can do that you have at your disposal when buying expensive stones such as diamonds. 

If you don’t have a diamond tester to do the job for you, relying on a simple flashlight is one of the most reliable means to check a diamond’s validity. 

The way real diamonds reflect light is unique and depends on the cut type and the diamond itself. Hence, when testing a diamond’s validity using a flashlight, you should note that two diamonds may not portray the same results.

Though both diamonds may be real, one may reflect little green or gray light, while the other glimmers with rainbow colors. This is dependent on the type of diamond you have in your hands. 

Final Thoughts

Diamonds are beautiful. However, a diamond that is fake is of no use. Hence it is important that you check the validity of a diamond to ensure that you have the real deal on your hands. 

At the end of the day, nobody wants a diamond that is not real, and all it takes is a flashlight to check the validity of a diamond. 

The flashlight test is one of the simplest and easiest ways to check whether a diamond is real. Just so long as you have a flashlight with you the next time you buy a diamond, nobody will ever be able to fool YOU!

FAQs

No, diamonds do not shine in the dark; they only glimmer and shine when light is present.

Yes, a flashlight can be used to test the validity of a diamond as it can reveal the diamond’s ability to disperse light, which is a tell-tale sign of a real diamond.

A scratch test for diamonds is a method of testing the authenticity of a diamond by scratching its surface against a mirror. If the diamond is real, it will leave a mark on the mirror; however, if the diamond is fake, it will not leave a mark.

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Author
Dillon Morrison
I have been involved in the flashlight community since 2007. My brother has a flashlight shop from where I have tested and reviewed more than 600+ different types of flashlights. You can find more about me here.

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