Skip to Content

How Does A Diamond Tester Work?

How Does A Diamond Tester Work?

We’ve all seen, at least in the movies, how a diamond tester looks and how it’s used, but do we know how does a diamond tester work exactly?

This question has been asked too many times to be ignored. So, we decided to go ahead and tell you all about the way this machine – that, by the way, is compact enough to fit in your hand – works and why it’s crucial.

Considering that there are too many fake diamonds out there, this device is valuable to anyone in the diamond world, regardless of whether they’re a diamond seller or a diamond buyer. It’s in everyone’s best interest to validate the diamonds in question.

We’ve taken an approach to this topic that will help you get the ins and outs of a diamond tester without going too deep into the technical and mechanical parts of the explanation.

We feel like most answers to this question are too hard to understand or have been written from a technical point of view – which doesn’t guarantee that the reader will actually understand that explanation.

Now that we’ve gotten that out of the way, let’s jump right in – and see how does this interesting device works?

What Is A Diamond Tester?

Before we get into a deeper explanation and tackle the details, we first have to take a look at what a diamond tester is, how it’s used – and what it’s used for, of course.

The name “diamond tester” may be a dead giveaway as far as that last bit is concerned, though. That’s pretty crucial since this information will help you better understand further explanations on this topic, so stay patient!

A diamond tester is a device used to check the authenticity of diamonds and test materials for their thermal and electrical conductivity. More importantly, it’s portable and easy to transfer – one of the reasons why it’s so convenient and widely used. 

These devices are often used to test diamonds in jewelry stores, diamond dealerships, and any other specialized store that handles buying or selling diamonds. The fact that “buying” and “selling” are mentioned here plays a huge role since one of these two scenarios does require more extensive use of a diamond tester.

Learn More: How Much Is A Diamond Tester?

A diamond tester is more often used when a store wants to purchase a diamond from someone – and there’s a good reason for this: Jewelry stores generally buy diamonds directly from the manufacturers of the jewelry pieces or diamond dealers. So, they do get a certificate of authenticity with that jewelry or the diamonds.

But when a person is trying to sell their diamonds, this is a totally different story. There’s no certificate of authenticity, or even if there is, it doesn’t mean it’s for the diamond in question.

You get where we’re going with this, huh? Diamond testers are used to check for the diamond’s authenticity and see if the stone presented to them is even a diamond.

You’d be surprised (or flat-out shocked) at how many people try to pass glass – or other similar materials – and synthetic copies as diamonds just to gain financial profits.

We’ll discuss the exact way of using a diamond tester a little bit later, but the only thing essential here is that it’s used much more often when a person is trying to sell their diamonds or jewelry pieces with diamonds in them.

Even when a person is trying to sell their diamonds to another person, it’s always good to have a diamond tester around. That way, both parties know that the diamonds have been validated – and can witness the actual authentication process. 

That last bit is important because – well, diamond switching is a thing. 

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

How Do Diamonds Testers Actually Work?

Now, it’s time to take a look at the situation from a technical and practical point of view and see how diamond testers work.

First off, bear in mind that there are two ways in which diamond testers operate and test diamonds: 

The first one relies on heat, and the second one is based on electric conductivity. These two methods are fairly similar regarding the end result, but they work in ways that are a bit different.

We’ll look at both of these and explain to you how both of them work individually. After that, we’ll discuss if there is a better method – and talk a bit about which one tends to be more accurate.

But for now, the only thing that’s vital to remember is that there are two ways in which diamond testers work – heat and electric conductivity.

Method #1: Heat

The diamond testers that work on the heat principle are a bit more common than the other ones since they’re generally more reliable – and can tell you the results faster than their electric-based counterparts.

Don’t get us wrong; both of these show results after just a couple of seconds. Still, there is a slight difference in speed, which may not seem important to you right now, but trust us – it is.

These heat diamond testers work by testing the conductivity of heat in the stone. Different gemstones have different heat conductivity levels, so diamond testers are made to detect the level of conductivity characteristic for diamonds.

All of these testers have a small needle-like rod at the end, which you then lean against any part of the diamond.

Then, you hold it there for a couple of seconds – and wait for the results.

Now, we feel like the heat conductivity we’re talking about here needs to be addressed, and that’s the part that involves numbers, so be ready:

The heat conductivity of a diamond is more than 2,000 Watts per meter per Kelvin which might not mean much to a significant majority of you, but it’s crucial for you to at least know what it is on paper.

Also, it’s important to note that diamonds are the best thermal conductors at room temperature – besides graphite and graphene, that is. And one thing that makes them all similar is that they all come from carbon.

So, now that we’ve gotten the physics portion of it out of the way let’s talk about how that looks in practice.

When someone presses the needle of a diamond tester against the diamonds, one of two things will happen, depending on the model of your diamond tester.

The first thing would be that the little built-in bar will show the heat conductivity level of the stone in question. Alternatively, there will be a sound signal – a long and steady beeping sound – telling you that the heat conductivity levels indicate that you’re holding a diamond.

Regardless of the way your diamond tester indicates the heat conductivity levels, the outcome is the same. 

So, you don’t have to worry about these two different types of testers giving you different results:

They give you the same results but in a different way. You can test your diamonds with both, but there’s a 99.9% chance you’ll get the same results.

Related Read:

Method #2: Electricity

Electricity-conducting diamond testers are popular and often used to test diamonds, especially in jewelry stores or diamond dealerships.

The heat models are usually owned by people for their private use, while electricity-conducting diamond testers tend to be preferred by professionals.

Now, a quick disclaimer: That doesn’t mean that this one is more reliable or more accurate. It just means that people in the diamond world prefer the models of diamond testers that work based on electricity.

In contrast to the heat-conducting characteristics of diamonds, diamonds are the exact opposite thing when it comes to electricity.

That’s the most significant difference between the heat and the electricity tests used to verify the legitimacy of a diamond.

Diamonds are electrical insulators which means they do not conduct electricity – but isolate it instead.

When a stone is tested using this method, the diamond tester looks for the isolation of electric currents, which would show that diamonds are genuine.

If an electricity conducting model of a diamond tester detects any electricity in the diamond, it will show negative results (or just won’t show positive results). And if there isn’t any electricity, that would indicate that the diamond tester is touching a genuine diamond.

These tests may seem better since there either is or isn’t any electricity in a diamond – which is true to a degree.

We firmly believe that this is why diamond dealers and jewelry stores dominantly use this kind of testing diamonds. We can’t be sure, though, since there isn’t any official information backing up this claim; it’s just our assumption. 

As far as the accuracy of the testers goes, we can safely conclude that the diamond testers that check for electricity in a gem are every bit as accurate – if not more – as their heat-conducting equivalents.

These testers are used in the same way that the heat-conducting ones. There is a needle on the end of the diamond tester that you press (gently!) against the diamond in question.

After that, you’ll be shown positive results if there isn’t any electrical conductivity – and negative results if there is.

These diamond testers often feature a tiny built-in display that indicates the levels of electrical conductivity where the green field is lit up if there isn’t any conductivity. And the orange or red field lights up if there is some electrical conductivity detected.

Also, there’s often a wheel at the top of these diamond testers that amplifies the electric energy searched for during the test. So, even if there is some – these fine diamond testers can catch a glimpse of it.

These testers are generally considered much more “delicate” than their counterparts. But these features aren’t used as often since some diamonds can have very little electrical conductivity in them – which doesn’t make them any less genuine. Take blue diamonds, for example. They can conduct electricity

In the end, we feel obligated to say that these diamond testers may have a bit higher price tag on them than the heat-based ones. Still, that doesn’t mean that you should trust them more than their heat conducting counterparts.

See Also: Do Black Diamonds Conduct Electricity?

Our Final Thoughts

Now that we have taken these testers apart and shown you how every variation works, it’s time to recap and see what we’ve said in this article in short notes.

First of all, two types of diamond testers are generally used – the heat-conducting one and the electricity-conducting one. Both are accurate and often used to check diamonds during a sale or just for validating their authenticity. And yes, both should show identical results. 

If you have both of these at your disposal, we highly recommend testing your diamonds with both and comparing the results. That’s the most accurate way of checking the diamonds you’re about to buy.

But, if you don’t – it’s entirely OK to trust one or the other.

Also, note that the models based on checking the electrical conductivity of diamonds are more often used by jewelry stores and diamond dealers. So, you’re much more likely to run into one of these.

That would be it as far as the diamond testers and the way they work goes. We hope that you have a pretty good understanding of this topic now – and we wish you the best of luck in your diamond testing ventures!

Related Read: