The Best Diamond Testers, Including Heat & Electric Options in 2024 – Best Gem Testers for your Gemstone

When it comes to buying gemstones or diamonds, you want to make sure that you are not paying too much for fake ones.

And the best way to do this is by using a gemstone tester before finalizing your purchase.

A gemstone tester is used to check the quality of gems and minerals before they are sold or given as gifts.

There are many different types of testers so it is important to know how they work.

Here, are some details about some of the most popular types of testers available on the market today. Please do not forget to read our FAQ further down the page.

How accurate are gem testers and how do testers work?

What you need to know is that diamond detectors either send heat or electricity to the diamond to test it. Basically, you inject heat into the surface of the gem (or electricity).

The way that electricity or heat transfers inside a diamond have a well-known pattern. This pattern is incredibly different from the way electricity or heat is transferred through other materials, like glass, and fake diamonds such as cubic zirconia, among other materials.

So, by just “injecting” a little bit of heat or electricity into a gemstone, the tester can tell you whether the diamond is fake or real.

This is the beauty of using these testers.

What you also need to know is that gem testers are extremely accurate. So, before spending any penny on buying a diamond, ensure you get one of these testers. You do not want to end up with a fake device.

What you must know about professional diamonds and electronic gem testers?

There are a few factors to consider when it comes to the accuracy of gem testers. The first factor is the type of tester being used. Some testers are more accurate than others.

The second factor is the skill level of the person using the diamond detector/tester. A skilled user can get more accurate results than someone who is not skilled.

The third factor is the condition of the gem being tested. If a gem is damaged or has been treated, it may not be able to be accurately tested with a standard tester.

Finally, the environment in which the gem is being tested can also affect accuracy. Temperature and humidity can both affect readings from gem testers.

Can Diamond testers ever be wrong?

This is a very valid question.

What you need to know is that diamond testers are probably one of the best and most accurate devices to check a diamond gem for authenticity.

However, you need to understand one major point. Diamond testing that relies only on thermal conductivity can, at times, mistake moissanite for a diamond.

The reason behind this mistake is that these two stones (moissanite and natural diamond) are quite similar in the way they conduct heat.

So, yes these precise diamond testers come with an extremely high accuracy factor, but you must know what you are looking for to avoid choosing moissanite instead of the real diamond deal.

#1. Presidium Gem Tester II – One of the best diamond testers on the market

If you want the best gemstone tester, the gem tester presidium II is the way to go in our opinion. It offers the best combination of durability, ease of use, reliability, and price.

It has one of the industry’s smallest probes coming in at just 0.6mm which is capable of very small detecting gemstones.

Our favorite part is that it is just easy to use, easy to read, and gives you consistent results each and every time.

Click here for more information

What is the Best Gem Tester and Gemstone Tester?

There are many gem testers available for purchase. It can be difficult to choose the one that is best for you. It will all depend on what you want to test and what your budget is.

Some gem testers are more expensive than others but they usually provide more information about the gemstone.

The price for these gems can range from $100 to $3000, so it may take some time and research before deciding which gem tester will work best for you and your budget.

As these testers are small in size, they are, at times, sold with nice little carrying cases.

Choosing the best tester

Here are the best testers that we researched, tested, and do the job perfectly:

#1. Presidium Gem Tester II – One of the best diamond testers

 Best Diamond Testers

For those interested in the best gemstone tester, we have to hand it over to the Presidium Gem Tester II.

This is definitely one of the industry standards and is the best value in our opinion. We like this instrument because it is incredibly precise as it can test very small gemstones down to 0.02 carats.

There is also a detachable probe pen with a retractable thermoelectric probe tip.

Overall, it is one of the few devices that include thermal testers and an electric one.

The standout feature is probably that it has one of the industry’s thinnest probe tips at 0.6mm. Also, it runs on 2 AA Batteries and the battery life is actually surprisingly pretty good.

Overall, this gemstone tester is simple and very easy to use. It has no waiting time between tests and gives you consistent reliable results every single time.

What is the presidium diamond tester’s accuracy?

The presidium gem tester accuracy is a term that is only used in the jewelry trade and it measures the accuracy of a gemstone tester.

When you purchase a diamond or precious stone, there is always some chance that it may not be as described. The presidium gem tester accuracy measures how often this happens.

The presidium gem tester accuracy is high. The precision is not less than 98%.

Presidium gem testers are accurate to an accuracy of 98%.

Click here for more information

#2. SmartPro SPGE-I Gem Eye I Gemstone Tester

Next up, we have the SmartPro SPGE-I Gem Eye I Gemstone Tester, which is the best gemstone tester for those who already know how to identify real and fake gemstones beforehand.

In other words, this machine is definitely not good for a beginner or novice who has limited knowledge of gemstones. You will need a good background knowledge of gemstones to properly identify them.

However, if you already consider yourself very knowledgeable, this instrument can be a great assistant. It is very consistent and always reliable as far as we can tell.

Just keep in mind that it is a very sensitive instrument and many things can throw off your reading, such as extreme hot and cold weather, a dirty probe, and clean material.

Click here for more information

#3. TekcoPlus Gemstone Tester

 Best gem Testers

Another pretty good option when it comes to the best gemstone tester is the TekcoPlus gemstone testing device. In essence, this diamond tester pen is simple.

This is definitely a nice budget-friendly option for those who want something cheap and reliable.

While it is certainly not as accurate or just well built as the above two brands, the TekcoPlus is definitely something respectable and will give you decently good readings if a stone is a real diamond.

This is a handheld device and comes with a fine elastic tipped probe used to detect various gems. In general, we find this dual diamond/moissanite tester to be surprisingly accurate.

However, it does have some pitfalls, namely the pitiful battery life and the fact that you have to wait a few minutes for it to “warm up” before using it.

Click here for more information

#4. Diamond Tester+60X LED Magnifying Glasses Jeweler Tool Kit Combo,for Novice and Expert Electronic Gem Testers

 Best Gemstone Testers

This diamond tester pen and 60x LED is a serious contender with the TekcoPlus for the best budget-friendly gemstone tester.

This one is seriously cheap, but does it hold up to the performance test? In general, yes, but there are a few caveats.

First and foremost, it is cheaply made and we feel like it can break pretty much anytime. In fact, it feels like a toy and quite unreliable.

Second, it works for many types of other stones as it tests hardness, but it doesn’t really give you that much information.

There is still a lot of stuff you have to interpret visually yourself. So is this cheap gemstone tester worth it? We think yes because it doesn’t hurt and actually helps you confirm some of your visual inspection.

Click here for more information

#5. Presidium Multi Tester III – Testing Diamonds, Moissanites, and Diamond Simulants

Gemstone Tester

Finally, the last product we recommend is the Presidium Multi Tester III, which is Presidium’s handheld gemstone tester. We really like it because it is like the portable version of their tabletop device.

It has a nice retractable tip and best of all there is no waiting time in between tests. It even has a built-in metal detector, which is a nice little bonus.

Like its tabletop version, it is very precise and accurate and can detect diamonds as small as 0.02 ct.

The user interface is also quite nice and has this nice 180-degree multi-view LED. It also has split-second test results, surface mount technology, and a nice ergonomic design with a nice sturdy anti-slip grip. This device definitely rivals its tabletop predecessor.

Click here for more information

#6. Gem Tester II (PGT II) – The best colored gemstone tester

Gemstone Tester

Presidium Instruments Gem Tester II (PGT II) is the best and the industry’s most trusted colored gemstone tester.

It simply easily identifies diamonds/moissanites. It can separate up to 16 common colored gemstones based on their thermal conductivity.

This tool is a handheld device that can be carried in your bag.

It has a color touchscreen and includes an Assisted Thermal Calibration (ATC) mode for more accurate results.

The ATC mode allows the user to input the gemstone’s color using the touchscreen, and the PGT II will then identify the gemstone based on its thermal properties.

This makes it an ideal tool for jewelers, gemologists, and other professionals who need to identify gemstones quickly and accurately.

Overall, this diamond selector ii will indicate genuine gemstones quickly with the industry’s most used device.

Click here for more information

Frequently asked questions – FAQ

Here are some of the most frequently asked questions answered by our experts.

What is the difference between the presidium gemstone tester and a jeweler’s loupe?

The presidium gem tester is a device that can be used to test the authenticity of a gemstone. It has a lens that magnifies the stone as well as measures its clarity and color. The jeweler’s loupe is an instrument that jewelers use to examine gemstones, but these are not that accurate and that’s why jewelers like a gem tester.

Having said so, loupes or magnifiers are the preferred tools used by diamond experts to look for nice gems. So, if you are an expert, then use a loupe, but if you are halfway through becoming an expert, then you’d better stick to a gem tester.

Do jewelry stores have the best gemstone testers?

Not all jewelry stores have diamond testers, but most larger stores will have one available for use. If you are looking to buy diamond jewelry, it is a good idea to ask the store if they have a tester before making your purchase. Be sure that they give you the methodology as to how to use the tester.

Do diamonds weigh the same as cubic zirconia?

Not at all. Cubic zirconias are heavier than diamonds. They, in fact, weigh about 55% heavier than diamonds. So if you have fake cubic zirconia, then it will weigh slightly more than a real diamond of the same size and carat. To perform this test, you will need two stones; one diamond and one cubic zirconia of comparable size.

What is the best fake diamond or gemstone?

Silicon carbide is one of the best imitations of diamond in existence. It’s almost as hard as a diamond (the Mohs scale rating is 9.5 on moissanite and 10 for diamond). As they are nearly colorless, Moissanites are nearly like diamonds. So watch out for fake gemstones made of silicon.

Which is better a diamond or heat tester?

Between the two devices, independent researchers have found that electrical conductivity testers are superior to thermal conductivity gemstone testers.

These electrical testers cost more but are more accurate and easily confirm the genuineness of diamonds. Heat testers are generally more affordable, but they are less precise and at times may not provide if a diamond is real or not.

Do Cubic Zirconia stones sparkle like diamonds?

The optical Refractive Index (RI) of Cubic Zirconia (CZ) is known to be between 2.15 and 2.18. On the other hand, the RI of a diamond is between 2.42 and 2.48. The higher the RI, the higher the brilliance of a gem. As we can see, the brilliance of a diamond is much higher than the one of Cubic Zirconia.

So, without a doubt, the diamond is the best of the two stones. The optic brilliance of diamonds is something that cubic zirconium can never achieve.

Final words on the best diamond testers 2022

It can be tricky to find the best gemstone tester. There are so many different models on the market, many with mixed reviews.

In this article, we have put a number of brief reviews of the most popular gemstone testers on the market today.

We had a look at what each model has to offer and gave you our opinion of which is worth your money. To be honest, the Presidium Gem Tester it the top tester you can find out there. It is simple to use a highly accurate.


The Review Gurus