Do you know how to tell a real diamond by eye?
That is what we are going to cover in today’s guide. We shall look at:
- 10 different ways to check if a diamond is real
- The #1 best way to know a fake diamond
- What to look for when testing
- And a lot more!
So how do you tell if a diamond is fake or real?
Unfortunately, many real and artificial gemstones look like diamonds but they are not.
Some of the gemstones that look like diamonds include white topaz, cubic zirconia, white sapphire, moissanite, white zircon and normal glass. These gemstones can be cut to look like diamonds.
If you are not keen, you could pay thousands of dollars for a glass that is shaped like a diamond.
Sounds crazy, right?
Gemstones that look like diamonds are referred to as diamond simulants or imitation diamonds. These stones are marketed as alternative diamonds.
You will find some jewelry stores advertising these stones as natural diamonds but they are not. It is not common but it can happen to anyone, not everyone has gemology knowledge. Luckily, there are several ways to know if a diamond is real.
Some of the tests we shall be highlighting are simple, some will need supplies while others need to be done by a local jeweler.
How To Tell a Real Diamond By Eye
1. The Scratch Test
Supplies needed
- Sandpaper or mirror
For so long, this has been the basic test to tell a real stone from a fake one. The process involves scratching a loose colorless stone against a mirror.
If the stone scratches, that is not a real diamond. If you don’t have a mirror, use sandpaper. A real diamond is very difficult to scratch, it is the most scratch-proof stone.
The Mohs scale is the standard tool used to measure how hard a mineral is. Diamond rates at position 10 on the scale, which is the highest hardness level a stone can have.
Is this test reliable?
This is a great test to tell a real diamond from a fake one, although other alternative stones can pass this test as well. Moissanite sits at 9.5 on the Mohs scale, and white sapphire (and all other sapphires) is rated a 9.
If you use this test on moissanite and sapphire, they will not scratch easily. For this reason, the scratch test is no longer reliable. But don’t worry, there are other tests you can use t ensure you are not paying for a fake diamond.
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2. The Fog Test
Supplies needed
- Your breath
- Tweezers (optional)
You can perform this test at home with a stone that is mounted or unmounted. If you decide to use a loose stone, ensure you are conducting the test where you can get back the stone if it slips from your hand.
Put a solid-colored towel on your bathroom sink for the diamond to land on if it slips. This will prevent it from bouncing to a place where it may be drained.
For this test, you need your breath and good eyesight. The fog test is among the oldest methods that still function effectively today. It is not 100% accurate, the results may be misinterpreted.
Use your fingers or tweezers to hold the diamond. Make sure you hold the stone in a way that you can clearly see the table (top side) of the stone. Then, breathe onto the stone the way you would do when fogging a window.
If the stone is a diamond, it will be difficult to fog it up because it does not retain heat well. A real diamond will fog up and disappear quickly. If the fog takes more than a few seconds to clear up, that is not diamond.
Is this test reliable?
There is a possibility that the results may be contested in this test. There is no set timeframe of how long it should take for the fog to disappear.
Also, humidity and temperature may mess up the timeframe needed for the fog to dissipate. So, this test should not be used as a confirmatory option on its own.
3. The Newspaper/Dot Test
Supplies needed
- Pen
- Paper/newspaper
Initially, this test was done with a newspaper, but today you can use any plain paper. Place the stone in question on the newspaper and specifically on top of the area with an article (not a picture or ad).
If you can see the letters through the stone, the stone is not a diamond. Because of the high brilliance of diamonds, it is not possible to see any lettering through them.
When using plain paper, make a dot on it using a pen. Put the stone over the dot with the stone’s table facing down. If you see a sparkle instead of a dot, you have yourself a real diamond.
This test is particularly helpful if you want to distinguish diamond from cubic zirconia because the latter is very transparent. Moissanite stone is also transparent.
Is this test reliable?
The plain paper or newspaper test is not a reliable method to tell a real diamond by eye. It is meant for big stones. Any stone less than 1/2 -a carat is difficult to see through.
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4. The Water Test
Supplies needed
- Water
- Glass
The water test is simple but can only be performed o a loose stone. It is not possible to do this test on a supposed or mounted stone. All you need for this test is a tall drinking glass. You have to be careful when holding a loose stone since it can easily drop.
Fill the glass with water about ¾ then drop the stone in the water. A real diamond will sink, and other stones and gemstones will float.
Some fake diamonds will hang around the surface of the water. Diamond has high density and its weight will push it down to the bottom.
Is this test reliable?
Do not take the results from this test as the gospel truth. Moissanite and cubic zirconia stones also sink in water because they are heavy.
Their density may not be as high as that of real diamonds, but they will still sink. This test helps sort out stones like glass, crystal, or quartz.
5. The Thermal Conductivity Test
Supplies needed
- Tweezers
- Diamond tester
This is commonly referred to as the dreaded diamond tester that generates horror stories, so be ready. It involves the use of a small handheld device that looks like a pen. The tip of the device uses thermal conductivity to test if a stone is real or fake.
You can use either a loose or mounted diamond but it’s easier to use one already mounted on an engagement ring. Hold the tip of the diamond tester against the stone for approximately 30 seconds. The way a diamond tester works is a bit complex. Some testers may light only if they identify the stone as diamond. Others may light if moissanite is detected. The tester may not say if the stone is cubic zirconia or any other diamond alternative. It just will not light.
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Is this test reliable?
Diamond testers are considered the most accurate technique, only if you use them right. If you have heard customers give their horror stories about a diamond at Kay or Zales failing this test, you should be worried.
A diamond tester is inconsistent. If a genuine diamond is dirty, the tester will not light. The tester may also give inaccurate results if it is placed on the stone for a short time or too hard. The tip should rest flat at the center of the stone. If positioned at an angle, you may get the wrong results.
6. The Jeweler’s Loupe
Supplies needed
- Jeweler’s loupe
This test can be done by a local jeweler near you or at home.
This test involves magnifying a diamond. You will need a jeweler’s loupe if you choose to test the diamond at home. You can find cheap jeweler’s loupes on Amazon. You will even find ones that come with UV lights and you can use the loupe to do a UV test. If you can’t find one, take the diamond to a jewelry store for them to test it.
When a real diamond is viewed under magnification, it reveals some inclusions, unless you bought a flawless, IF or VVS diamond. You should see inclusions that are appropriate for the clarity grade of your diamond.
Keep in mind there is no flawless diamond that is cheap. Moissanites and cubic zirconia stones look too flawless. Moissanites have inclusions but most of them are generally flawless.
Is this test reliable?
If you have a 10x magnifier or any other above that, you should not find it hard to see the inclusions that distinguish real diamonds from fake ones. You can even perform this test with a 10x magnifying glass.
If you bought a diamond at a very high price and you can’t find any inclusions, you may want to consider testing the diamond using another method.
This technique works best if the diamond is already bought. If you find a colorless stone and you want to test if it is diamond, this is not the best test.
The stone can be white sapphire if it has wispy or feather-like inclusions.
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7. The UV Light Test
Supplies needed
- UV light/blacklight bulb
Before you start this test, make sure you have a genuine black light since there are many fake options online.
Start by setting the test stone on a black background. The best place would be in the jewelry box so you get a great view.
Then, shine the black light on the stone. The stone will glow blue if it is diamond. The fluorescence in the diamond is responsible for the diamond’s blue glow.
You may be familiar with this term as it is commonly used in grading reports or diamond descriptions online. Fluorescence is normally listed alongside polish and symmetry.
Is this test reliable?
A diamond glows blue, so when you see a blue reflection, that is a diamond. However, if it is not blue, don’t be so quick to conclude it is fake.
Diamond fluorescence can be either None, Faint, Strong, or Very Strong. This means if the diamonds do not glow blue, their fluorescence could be None.
If the diamond does not glow or glow a different color, try another test or take it to a jeweler for confirmation.
8. The Candle or Lighter Test
This method uses heat to tell if a stone is read diamond or not. For this test, you will need a candle flame or lighter, a glass of ice-cold water, and tweezers.
You need to be very careful when performing this test. Only do it on a loose diamond. Do not try to bring the heat close to a mounted diamond.
Hold the mystery stone using the tweezers and bring it close to the flame. Keep it there for 30 seconds. If the diamond is real, there should not be any reaction because real diamonds are heat resistant. A fake diamond will shatter immediately.
If the stone does not react to the heat, it will be dirty after the test. You need to clean it by soaking in a mixture of water and toothpaste for 5 minutes. Use a toothbrush to scrub any residue on the diamond.
Is this test reliable?
This test is quite reliable but not completely.
Some diamond substitutes like zircon and moissanite are also heat resistant.
White sapphire and cubic zirconia will shatter. White topaz will change color if you use a jeweler’s torch.
9. The Sparkle Test
If you have been reading our guides, you know by now that diamonds sparkle. But do you know that you can tell if a diamond is genuine depending on how it sparkles? For this test, you need very good eyesight.
Hold the stone in question under a lamp and observe the brilliance. Diamonds are known to have a balanced mixture of white light and rainbow light. In other stones like moissanite and cubic zirconia, the rainbow light overpowers the white light. It’s almost like the stone has rainbow colors only.
If the stone is too brilliant, flashy, or excessively dull, it is not diamond. Even the worst cut diamonds have admirable sparkle when put next to a white topaz or white sapphire.
Is this test reliable?
This test is somewhat reliable if you know what you are looking for. It is the best test if you have another stone to act as the control experiment. However, if you know nothing about diamond brilliance or cannot tell the difference without another stone, use another test or take the diamond to a jeweler.
White zircon is the closest to diamonds when it comes to brilliance but it is never promoted as such. Most jewelers prefer moissanite as the first alternative to diamonds followed by white sapphire. White zircon has double refractivity. In genuine diamonds, refraction goes into the diamond and reflects out as a ray going in one direction. Double refraction also referred to as birefringence is where the ray splits into two and the rays go in different directions.
10. Checking Marks on the Diamond Ring Settings
This is more of an observation than it is a test, but it can still help differentiate a real diamond from a fake one. It is one of the least effective methods to use especially if you are trying to find out if you have been sold a fake diamond. It can be used on loose diamonds as well as mounted diamonds.
In most cases, diamonds that are 1+ carat are normally set in precious metals like yellow gold, white gold, rose gold, sterling silver, or platinum. In compliance with regulations set by the Federal Trade Commission, all fine jewelry set in solid metals must be stamped.
Solid gold metals are normally stamped as 24K, 22K, 18K, 14K, or 10K. sometimes you will see KT. Look out for stamps marked 14KGF or 14KGP which means that the metal is not solid gold. KGF stands for gold filled while KGP stands for gold plated. These stamps mean that there is a thin layer of gold on top of another metal. The base metal could be stainless steel, copper, sterling silver, or brass.
Most diamond substitutes are not set in precious metals, instead, they are set in cheaper metals.
Is this test reliable?
This test is not a confirmation that the stone is actually diamond. You can find moissanite or cubic zirconia set in platinum or gold but it is rare. You can find cubic zirconia set in solid gold online but never in physical jewelry stores.
It is worth noting that not all gold-plated jewelry is always stamped. You can’t sweep under the carpet the fact that gold plated can be stamped instead of solid gold. If the jewelry bears no stamp and you have no way of telling if it is solid gold, take it to a trusted jeweler for testing.
Conclusion: How to Tell a Real Diamond by Eye
So, you now have 10 different ways to check if a diamond is real. If you have noticed, no one test is 100% reliable.
Mere one test is not enough to tell you if the stone you bought is a real diamond. However, if you subject the mystery stone to a few of these tests and you come out with positive results, then you can rest assured that you have a real diamond.
Even if you conduct several tests and the stone leans one way, you should still take it to a trusted jeweler who is not affiliated to any diamond retailer. Such a jeweler will not give you the results that the retailer wants you to have. You can trust gemologists and bench jewelers to give you authentic and reliable test results.
Even if the diamond you have passes the test, keep in mind that there are synthetic diamonds in the market.
Lab-grown diamond engagement rings are more or less 50% cheaper than natural diamonds with the same grades. There is no significant difference between the two, both are genuine diamonds.
A natural diamond is formed in the earth’s crust over billions of years while a lab diamond is created in a simulated environment and takes only a few weeks to fully form. They have the same characteristics.
Lab diamonds don’t have any resale value and cannot be traded in like natural diamonds.
If you are looking for the best place to buy synthetic diamonds, head over to Clean Origin or James Allen.
It is not easy to differentiate a fake diamond from a real one, even jewelers find it hard. Highly skilled jewelers know how to tell the difference. The likelihood of finding a fake synthetic diamond is slim. If you are worried about being sold a lab diamond instead of a genuine one, the best you can do is take it to a jeweler.
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