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What Happens When A Diamond Tester Beeps?

What Happens When A Diamond Tester Beeps?

Diamond tester is a portable gadget that helps test gemstones. It’s so tiny that it fits in your pocket. And, well, this tiny device features a needle-like tip that’s placed on the stone that’s being tested. The question is: What happens when a diamond tester beeps?

If a diamond is genuine, the gadget will indicate that on its display or with a beeping sound signal, and you’ll know that your stone is an authentic diamond. 

But how does a diamond tester work, anyway? In this article, we’ve covered everything you need to know about diamond testers, as well as some at-home tricks you can use to check whether your stone is a real diamond. 

So, without further ado, let’s dive in.

How Does A Diamond Tester Work?

Diamond testers use a needle-like, retractable tip on the top of the device to help determine if a diamond is genuine or not. This tip relies on measuring thermal conductivity to give an accurate result.

To use a diamond tester, simply place the tip on the top of the precious stone for a few seconds. The thermal conductivity levels are calculated – and if that diamond is real, the gadget will notify you. 

If the device determines that the stone is a real diamond, it will either show a positive symbol on the display or emit a steady beeping sound to confirm the results. 

The entire process is finished within seconds, so you don’t have to sit around and wait for the results.

Learn More: How Does A Diamond Tester Work? – Details Of A Device Validating Your Diamonds

How Reliable Are Diamond Testers?

Diamond testers are, in fact, one of the most reliable ways to determine if a diamond is real or not. Most jewelers use one of these devices to test stones before they buy or sell them.

Certain models could give inaccurate results, though, so it’s essential to purchase a tester from a reliable brand. Sometimes, a diamond tester can mistake moissanite for a diamond. 

Can you do something about it? Well, to combat this, you might want to get a diamond tester that measures not only thermal but electrical conductivity, as well. 

So, while there are some issues and “fake positives,” they’re generally pretty accurate. 

Read More: Can Diamond Testers Be Fooled?

Diamond Tester Price

You can find standard, conventional diamond testers ranging from $15 to $20. As for moissanite testers, they’re available from roughly $20 to $30. And a bit more professional jeweler diamond kit can be found for around $40.

Learn More: How Much Is A Diamond Tester?

Types Of Diamond Testers

There are different types of these handy gadgets available on the market. The conventional tester with the retractable heating tip is slowly being replaced by some other methods of determining whether a diamond is genuine or not. Let’s take a look, shall we? 

Thermal Diamond Tester

The conventional or thermal diamond tester consists of two thermistors and a small copper tip. This one is a “traditional” type of diamond tester where the point is heated and placed on the stone’s surface. 

The high-temperature sensitivity makes this a very accurate and reliable device. However, this instrument is very delicate – and needs to be handled with care.

Electrical Conductivity Diamond Tester

This type of diamond tester works in a similar principle as the conventional testers. It’s just that it doesn’t use heat conductivity but rather electrical conductivity to determine whether a diamond is genuine. 

Moissanite testing is done through electricity as they’re electrically conductive – unlike genuine diamonds.

The Diamond Tester Pen

The GIA pen is a device that operates differently to differentiate “good” diamonds from the less genuine – or fake – ones. As per the GIA, diamonds show a particular affinity towards grease or greasy liquids.

The fountain pen-like device contains a particular type of liquid that leaves visible marks on the otherwise non-absorbent diamonds. If placed on any other gemstone, this greasy liquid will bead up – and it won’t leave any distinct image of any kind.

Fluorescence Diamond Testing

This type of diamond testing is utilized to check if diamonds are synthetic. All diamonds have fluorescence to some degree. However, lab-grown diamonds never have fluorescence. 

So, this type of testing is suitable for determining whether the diamond is natural or lab-grown.

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How To Use A Diamond Tester At Home

Here’s a step-by-step guide for using conventional diamond testers:

  1. Always clean the stone before testing it
  2. Gently remove the protective cap from the needle tip
  3. Hold the diamond tester in your hand and press the probe tip at a right angle onto the stone. Don’t press the tester at an angle lower than 90 degrees
  4. When testing diamonds that are mounted in a ring setting, hold the ring with your other hand
  5. For loose diamonds, placing them in the testing base yields the best results. Secure the testing base with one hand

An important thing to remember is to press the probe gently against the stone as too much force can bend or break the probe tip.

Can Diamond Testers Be Wrong?

Diamond testers can fail in many ways – and they don’t always have perfect accuracy. A few basic reasons why diamond testers can be wrong:

  • The battery is dying
  • You accidentally hit a prong of the ring
  • The diamond could be moissanite
  • The top of the probe could be loose, bent, or worn down

When Am I Likely To Use A Diamond Tester?

You’re likely to come across diamond testers in several different situations that require checking the authenticity of diamonds. Here are some common examples.

Selling Or Loaning

If you’re looking to sell or loan your diamond, it would be a standard procedure for the dealer you’re working with to use one of these devices to test whether your stone is a real diamond. 

That way, they can be sure of its authenticity before making an offer.


As a potential customer, it’s worthwhile asking the jeweler or dealer to test the precious stones you’re looking to buy right in front of you. Thay way, you can ensure that you’re getting a good deal for authentic diamonds – and not just nice-looking fakes.


Very often, your diamond jewelry will disappear from view while experts are repairing it in their workshops. And that’s when you might fall victim to diamond switching.

If you feel paranoid, it’s worth getting the jeweler to test your repaired jewelry in front of you when you come to pick it up. They should gladly do it as a part of their professional service.

Read Also: How Do You Avoid Diamond Switching At The Jeweler?

What Makes A Good Diamond Tester?

Make sure that your diamond tester uses not only heat but electrical conductivity, as well. That way, you can tell a diamond from moissanite. The latest models on the market generally combine heat and electricity testing, which makes them more accurate.

Another essential feature is a metal detector that signals if you touch the metal setting instead of stone by accident. And speaking of additional features…

Handy Diamond Tester Features

If you’re looking to purchase a diamond tester, keep in mind a few extra beneficial features that you might want your device of choice to include. Let’s go over a few together.

1. Retractable Tip

Since diamond tester tips have to be highly sensitive in order to do their job, they are incredibly delicate, too. 

Look for a device that features a retractable tip, as it’ll make sure you apply the exact amount of pressure to the surface of the tested stone.

That way, the tip protects itself from human error – and, in turn, you won’t need to spend money on repairs or replacement.

2. Quick To Reach Testing Temperature

Conventional diamond testers tell a diamond apart from other gemstones by measuring thermal conductivity.

As the tip of the tester heats up, you place it against the room temperature surface of the stone you want to test. And when you do this, heat is transferred naturally from the warmer tip to the cooler stone. 

The diamond tester receives thermal conductivity readings from this process.

So, if you want to test multiple stones in one sitting, you would probably like to have a diamond tester that reaches testing temperature and returns to normal temperature quickly and reliably. 

That way, your previous readings won’t mess with your later testings.

3. Differentiating Between Metal And Gemstones

You’ll probably need to test gemstones that are already set in a metal jewelry piece.

So, you’ll want a diamond tester that can identify if you’ve placed its tip on the gemstone or you accidentally placed it onto the metal setting of the ring.

If you buy a lower-quality diamond tester, it might not include this feature that warns you if you’re testing the metal setting instead of the stone. So, you could end up with inaccurate readings.

4. Accuracy Across Varying Ambient Temperatures

Most diamond testers work on the basis of testing thermal conductivity – that’s how they tell the genuine diamonds from fake ones.

So, you don’t want your device getting muddled up due to a change in ambient temperature, do you? 

The higher the quality of the tester, the better it’s equipped to deal with changes in surrounding air temperature – ensuring even more accurate readings.

5. Battery Or Mains Powered

Cordless, battery-powered diamond testers give you more flexibility. However, you might want the option to hook your device up to the mains. Some models offer both options built-in, so be sure to check their product specifications for this feature.

Other Ways To Check A Diamond’s Authenticity

If you don’t own a diamond tester – and you don’t plan on buying one – there are several tricks you can try at home to check if your diamond is genuine.

Water Test

Fill a normal-sized drinking glass with water and carefully drop the stone into it. If the gem sinks, it means it’s real. However, if the stone floats underneath or at the surface, you’re dealing with a fake.

A real diamond has high density; therefore, this test shows if your stone matches this high level of density.

Fog Test

For this test, hold the stone between two fingers and breath a puff of air on it. You’ll see a light fog on the surface of the gem due to the moisture and heat in your breath; that’s normal. 

If the fog disappears right away, the stone is actually a real diamond. However, if it takes several seconds for it to disappear, it’s likely a fake diamond.

Diamonds are great heat conductors and, therefore, have the ability to disperse heat quickly.

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Newspaper Test

To test the diamond’s refractivity, place the stone on a newspaper page in a spot with a lot of text. Ensure the lighting is bright and that no object is casting a shadow on the precious stone.

If you’re able to read the letters through the stone – even if the letters are a bit blurry – you have a fake one on your hands. If the stone is a genuine diamond, its facets will refract the light in all directions, rather than in a straight line.

Due to the refraction of the light, you won’t be able to see clearly through a real diamond. 

This test is most effectively used on loose stones, though. So, if your gem is already mounted in a setting, consider using the fog test instead.

The Dot Test

If you don’t have any newspaper, you can utilize the dot test as an alternative.

Place a blank piece of paper on a flat surface, draw a small dot with a pen, and lay the stone onto the dot. Through the pointed end of the stone, look down onto the paper. 

If you’re able to see a circular reflection within the stone, it’s fake. But if you can’t see the dot or its reflection within the stone, then it’s a real diamond. 

Due to the diamond’s refractive qualities, the light bounces in all directions, and that’s why you won’t be able to see dots or letters through a genuine diamond.

Learn More: How To Tell If A Diamond Is Real?


So, you decided to check your diamond’s authenticity with a diamond tester, and it emitted a beeping sound. What happens when a diamond tester beeps? 

Lucky for you, when a diamond tester beeps, that’s an indicator that you have a real diamond on your hands.

Conventional diamond testers use heat conductivity to check whether or not a diamond is real. Still, there are testers that use electrical conductivity – primarily used to check if the stone being tested is moissanite. 

Whether you’re selling, buying, or repairing your diamond jewelry, you will likely come across diamond testers. They’re an excellent way of providing you with that crucial information – and giving you peace of mind if you own a genuine diamond.

Apart from diamond testing devices, there are some methods you can use at home to check if your stone is real or fake. However, these aren’t as accurate as diamond testers.

See Also: Do Black Diamonds Pass Diamond Tester?