Top 5 Diamond Testers to Make Sure Your Diamonds are Real!

If you’re in a hurry and just want to find out what the best diamond testers are, then I’d recommend Presidium Adamas diamond testers as the best.

We spent 54 hours testing 24 products over 26 days to bring this article to you! The best diamond testers are designed to accurately and quickly test the authenticity of diamonds. These testers use advanced technology to provide reliable results, making them essential tools for jewelers, gemologists, and diamond enthusiasts. With their user-friendly interface and precise measurements, these testers offer peace of mind when it comes to verifying the quality of diamonds. Whether you’re buying or selling diamonds, having the best diamond tester can help ensure that you’re dealing with genuine stones.

Whether you are a beginner who’s curious about gemstones or an expert who values precision and consistency, my reviews of the top 5 best diamond testers are here to help.

The Top 5 Best Diamond Testers for 2024 are:

Here are the diamond testers we’ll be reviewing:

What we looked for:

Here are the main decision-making factors we looked for when evaluating the diamond detectors.

  1. Accuracy: The most important factor when considering a diamond tester is its accuracy in detecting real diamonds from imitations or simulants.
  2. Ease of use: A good diamond tester should be easy to use and provide clear and reliable results without requiring extensive training or expertise.
  3. Portability: Consider the portability of the diamond tester, especially if you need to use it on-the-go or in different locations.
  4. Durability: Look for a diamond tester that is durable and built to last, as this will ensure long-term reliability and performance.
  5. Testing capabilities: Some diamond testers may have additional testing capabilities for other gemstones or materials, so consider whether these features are important for your needs.
  6. Price: Compare the cost of different diamond testers and consider how it fits within your budget while still meeting your requirements for accuracy and functionality.
  7. Reviews and reputation: Research customer reviews and the reputation of the brand or model you are considering to ensure that it has a track record of quality performance.

How to choose the best diamond tester.

I’ll be focusing on two main factors which make the selection process easier for both beginners and pros:


You can see a few diverse models on our list and those on other similar guides. Brands like Presidium are quite popular in the jewelry market.

However, I don’t want to just blatantly suggest specific brands. That’s why you should always research for fair, representative information of brands and products that are all chosen on their innate quality.


You should be ready to spend on a range of price tags when looking for diamond testers, from affordable to slightly more taxing on the wallet. On average, the price of the diamond testers range between $15-$450. Higher-end testers range between $500-$1,200.

What you should look for in a diamond tester

Before we dive into which diamond tester you should pick, you’ll need to consider a few things. In this way, you’ll rest assured that you invested in the right one for your needs.

Ease of Use

If you’re a beginner, you’ll want a modest and comfortable tester to use so you won’t waste time on setup and analysis.

Most devices come with both sound and visual cues, making them ready for immediate use. So, if you’re someone who visits busy auctions instead of being the analyst, it’s best to go for portable and pocket-sized ones.


The two types of conduction used by diamond testers are based on heat or electricity. But which is more superior than the other?

Of the two, I’d say that electric conduction testers are a lot better than those that use heat conduction. While they are typically more expensive, you manage to get more accurate results. Heat testers, on the other hand, are cheaper, so they’re useful for on-budget users.

Here are my picks for the best diamond testers.

Best Low-End Heat Diamond Tester – StillCool

I enjoyed testing StillCool’s diamond tester since it’s so inexpensive and portable. You just quickly use it to pick genuine diamonds out of the fakes, without needing to spend too much. It can be used on all stones but will only denote real diamonds in the process.

The tester relies on batteries, so it’s easy to use. Its functionality is also simple, so it will immediately warn you both vocally and visually about the stone’s authenticity. The device can test both bulky and compact shaped diamonds and uses a primary switch to start.

I didn’t need to speed through the manual to figure out what the green light meant. Even so, most beginners will find their detailed instructions quite useful to figure out how to operate the tester. So, StillCool’s device would be the ideal choice for on-budget jewelers.


  • Portable
  • Affordable
  • Visual and audible indicators
  • Ideal for novices


  • Does not come with batteries
  • Not as accurate
  • Only works on diamonds

>> Check Price on Amazon <<

Best Mid-Tier Heat Diamond Tester – TekcoPlus

Not as costly as the first option, and just hitting the mid-tier section of diamond testers, we have TekcoPlus diamond tester. While not the most globally well-known brand, the price and quality still manage to make this a worthy investment.

Because of its cost, most professionals would choose to avoid the device. They’d prefer a few more features in the mix. That said, this diamond tester is still one of the most accurate tools I found. It can detect diamonds, moissanite, and even some metals apart from gold.

My tests saw that most diamond testers with lower price tags did not precisely and reliably check stones below 0.25 carats, which is why TekcoPlus manages to be so accurate. However, it has a half-minute warm up time, with a shorter battery time.

If you want a device that’s more catered to accuracy than the number of features, you can rely on TekcoPlus.


  • Accurate
  • Affordable
  • Clear display
  • Detect diamonds and moissanite


  • Generic brand

>> Check Price on Amazon <<

Best Low-End Electric Diamond Tester – Presidium II

Presidium’s Gem Tester II features a more compact, lightweight, and durable design than its predecessor. It’s more for professional use, so auctioneers and the like will enjoy the features a lot more than novices.

While thermoelectric, the tester primarily relies on the heat for its results. While less accurate than electricity, it still gives quick and precise results on a clear analog display. It works on moissanite, diamonds, and 16 other stones, offering a wide testing variety.

The new design comes with built-in calibrations that are interchangeable, depending on whether you’re indoors or outside. It is also known to have the slimmest retractable tip on the diamond tester market, test stones as tiny as 0.02 carats.

I was pretty okay with investing in the Presidium Gem Tester II for precise results and zero wait time.


  • Stones can be polished/unpolished
  • Consistent
  • Can use AA batteries
  • Can be used on smaller stones


  • Costly

>> Check Price on Amazon <<

Best High-End Electric Diamond Tester – GemOro

GemOro’s Ultratester is one of the most sensitive and accurate devices I got my hands on. The patented build makes use of a stylish and ergonomic handheld design for portability and ease of use. It is also versatile in function, being able to test multiple gemstones besides diamonds.

The tip is glowing, and the cone indicator has a simple red/green system to denote authenticity. You also get an LED diamond illuminator for clear visibility, along with an audible warning. You can detect diamonds, white sapphires, metals, and moissanite with the device easily.

The probe is sturdy and protected with a spring-loaded cover. The warmup time is also minimal at 10 seconds between tests. While not in use, there’s the auto-off function helps save battery as well. So GemOro’s user-friendly design and top quality make it a favorite on my list.


  • Quick warmup
  • Sturdy and covered tip
  • Comfortable grip
  • High quality


  • Cone indicator can malfunction
  • Costly

>> Check Price on Amazon <<


Best High-End Electric Diamond Tester – Presidium Adamas

The Presidium Adamas is precise on diamonds as tiny as 0.02 carats. It also comes with an additional micro tip for a 0.01-carat accuracy range. I can certainly see this in most actions and jewelry stores.

The probe tips are adjustable, meaning you get to replace the probe tip if it’s damaged or worn out. This feature is handy since spending on new testers is a lot more costly than replacing the tip. Add in the ability to test diamonds, moissanite, and simulants alike; it comes in quite handy.

The tip is also thermoelectric and uses USB charging. So, the device is easy to carry around and charge in any location. The standout feature is the inbuilt memory chip that has a test amount of up to 500. So, if you’re willing to splurge, the Adamas is an ideal choice.


  • Accurate
  • Lightweight and portable
  • Dual power source
  • Built-in memory chip


  • Costly

>> Check Price on Amazon <<

My Recommendations

That’s about all the information I have for you guys. We could delve even deeper into different price points, features, and variations in models. But I can’t make the final decision for you. Just remember the basic features and your needs, then picking the ideal product should be easy.

I focused on pricing, accuracy, warmup time, durability, and ease of use for my pick out of the best diamond testers.

Based on those requirements, I decided to go with the Presidium Adamas diamond tester as my winner for the best diamond tester.

The tester had the highest accuracy of all the devices I tested and one of the most effortless designs. It felt comfortable during handling, and the cost made me feel relieved knowing I invested in quality.

I would ideally recommend the Adamas for professionals. That said, if the device seems too daunting for you, then any of the low- to mid-tier options listed above should be just fine as well. I hope this article helped you with your diamond testing journey!

Carl A. Jones, GIA GG

Carl A. Jones is a GIA Graduate Gemologist with over 20 years of experience in the diamond industry. He is an independent jewelry appraiser. He specializes in determining the value of diamonds and advising consumers on how to buy quality diamond jewelry.

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