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Can You Test a Sapphire With a Diamond Tester?

Can You Test a Sapphire With a Diamond Tester?

Sapphires have been a popular choice for jewelry for a long time now. Sure, diamonds hold the number one, but sapphires can be a beautiful centerpiece for an engagement ring or a necklace. 

However, testing the gemstones is of the utmost importance when you are looking to purchase a new piece of jewelry. You need to check if everything is up to par, and when you are buying a diamond, you can simply use a diamond tester.

So, can you test a sapphire with a diamond tester? Is there a better way to test sapphires for their authenticity? Read our article to find out everything!

Can You Test a Sapphire With a Diamond Tester?

Diamond testers are a popular choice to quickly check a diamond for its authenticity. However, does that apply to all other gemstones, or are diamond testers strictly reserved for diamonds?

Well, for the most part, you cannot check gemstones for their authenticity using a diamond tester. As the name says, diamond testers can test diamonds – including lab-grown diamonds and moissanite – but you can also use them to check other gemstones. 

Because of that, sapphires can pass the diamond tester as genuine gemstones. Sapphires are a different gemstone than diamonds, but diamond testers work on most rocks. 

Diamonds have high thermal conductivity, and they will sparkle in all colors of the rainbow, while sapphires will mainly sparkle from white to silver. That doesn’t mean your sapphire cannot pass the tester, but that doesn’t apply to all gemstones – rubies can sometimes fail the test because of their deep color. 

Diamond testers work best on diamonds, but you should be wary of the results, let alone sapphires, even for diamonds. That is why you should do a more elaborate test of your sapphire to determine whether it’s genuine or not. 

Related Read: What Happens When A Diamond Tester Beeps?

How to Determine if Your Sapphire Is Real?

You may have gotten a new sapphire ring or inherited a piece, but either way, you should check if the gemstone is genuine. Luckily, you do not have to go to the jeweler right away – there are plenty of methods you can do yourself to see if your gem is real. 

You don’t have to contact a specialist just yet; you can do various techniques to check if your sapphire is natural at home!


Before you do anything else, you will need to check if your sapphire crystal is imperfect – whether it has some kind of inclusions or cloudiness. If you cannot see anything, use a regular magnifying glass to see your gem’s surface better. 

Look at the gem – if it looks close to perfect, it might be a fake gemstone. Genuine gemstones always have some degree of impurity and inclusions, and you will be able to see some with a magnifying glass.

Natural, real gems have inclusions all over them, and if they don’t have some kind of imperfections, they are likely fake. Sure, you can find some almost flawless sapphires in the wild, but it’s not expected – they are often imitations made out of glass or lab-made. 

Some inclusions can be seen with the naked eye, but most cannot. Hence why you should use a magnifying glass to check your sapphire stone. 

If you have never inspected a sapphire or any kind of gemstone before, there are a few things you should look for. First, look for needle-like inclusions, which are long and thin, and they often appear in groupings, so it looks like pieces of string. 

Needle inclusions are often called silk because several inclusions can cross, making them look silk. The texture of needles is silky and white, and they are sometimes transparent.

You have inclusions called mineral crystals – which are essentially natural. They are located inside the gemstone, and they can appear lighter or darker in color compared to the sapphire. They are a great sign that you have a genuine sapphire in your hands. 

Then, you should look for feather-like inclusions. They resemble real feathers, and these inclusions are usually white or very light in color. Feathers, however, can not be seen with the naked eye, and sometimes even the magnifying glass won’t help, but a microscope surely will. 

There are also fingerprint-like inclusions that are frequently found in sapphires. The inclusions are grouped together and strangely resemble a human fingerprint. 

Lastly, you will need to pay attention to the color zoning of sapphires. Sapphires are primarily blue, meaning sapphires don’t come off like any other secondary color; they are just blue. However, color zoning can make some parts of your sapphire crystal appear a paler shade of blue than the rest. That happens because of severe inclusions, making your sapphire appear whiter. 

Breath Test

After looking for the flaws of your sapphire, it’s time to perform a simple but effective technique called a breath test. Breath tests are a great way to establish whether you have a genuine rock in your hands or not. 

So, to do the breath test, you should take your stone and blow it into it to fog it up. Then, track how long your sapphire is foggy before it goes clear. Genuine stones take less time to clear – only a few seconds before the fog disappears. On the other hand, glass stones – or fake ones, to be exact, take more time to clear up compared to natural rocks. So, if your stone de-fogs quickly, it’s a real one.

Texture Check

Despite sapphires being naturally imperfect for the most part, there are details in the texture that appear only in fake gems. Fake gems can have air bubbles inside them because they are typically glass.

However, natural sapphires don’t have air bubbles ever – their texture is more silky and perfect in that sense. In fake gems, air bubbles appear from the synthetic manufacturing process where the sapphires are created with glass.

So, to check for air bubbles, take the crystal in your hands and look at it from all angles. You can even use a magnifying glass to help you determine if the stone is natural and worth some money.

Related Read: Can Diamonds Have Air Bubbles?

Scratch Test

Along with the breath test, the scratch test is a popular technique to determine the authenticity of a gemstone, including diamonds. If you have two sapphires and you know one of them is confirmed, you can use it to check if the other one’s genuine. 

Use the real one to scratch the surface of the suspicious gem and inspect the surface. If the suspicious gemstone got a scratch – it’s certainly not real. Sapphires are very hard, so it’s not real if you see a slight scratch. 

Related Read: Can You Scratch A Real Diamond?

Light Reflection

Gemstones such as the sapphire crystal reflect light in a certain way, and you can check how well your sapphire reflects light. Darken the room entirely and use a flashlight (you can even use the one from your phone) to check it out. 

Real sapphires reflect the light of the same color of the sapphire exclusively, without so much as a hint of another color. On the other hand, fake sapphires reflect different colors since they are made of glass – and it’s a tell-tale sign you have a fake in your hands.

Visit a Gemologist

If you did all the tricks listed here, and you still aren’t too sure about the origin of your gem, visit a good gemologist. Ask your friends or look for good reviews online to ensure you’re going to a qualified specialist first.

Sapphires come in all shapes and plenty of different shades of blue so that they can look suspicious to ordinary people. Gemologists can ensure you have a genuine sapphire in your jewelry better than you can at home.

Gemologists have nifty helpers at their hands to determine the authenticity thanks to their particular tools, such as unique scopes and refractometers. Once the gemologist is done, they will write up a report saying whether your sapphire is real or fake. 

The gemologist can also tell you more about the quality of a genuine sapphire. For example, if the gem has been heat-treated, they can tell you more about the degree of these treatments. Heat-treated sapphires don’t harm the stone, but they can decrease the gem’s value by at least a half, so it’s good to know if you want to sell the rock.

Determining the Value of Your Sapphire

Sapphires are one of the most well-known colored gemstones, and they are minerals in essence and emeralds and rubies. Sapphires are commonly blue, but several ‘fancy’ sapphire colors are pink, yellow, purple, and violet. They are all sapphires, but the color determines the price significantly. 

The blue sapphires are the most in-demand, and they often come with the belief that they are of the highest quality. The best sapphires out there are deep blue, with a hint of a violet tint, and they are medium to intensely dark blue. The lightest sapphires are worth the least, and sapphires are a bit gray or almost black. It’s safe to say that the middle works best and is priced the highest.

As for the inclusions, it’s natural for mineral-based gems to be severely included. Luckily, sapphires aren’t as heavily included as rubies and emeralds. Sapphires have a better grade of clarity in general. 

However, you cannot expect a sapphire to have high clarity, as such sapphires are very rare to find, and therefore, they are costly. We have talked about the specific inclusions sapphires can have – and these shapes of inclusions typically appear in sapphires exclusively.

The clarity grade is essential for sapphires because it determines how durable the gemstone is. However, it’s important to note that some inclusions can make a sapphire more expensive. For example, Kashmir sapphires have unique inclusions that make them look velvety, making them pricier than other gems.

The cut is also something that affects the value of sapphire crystals significantly. The sapphire has to be cut according to its rough shape, and because of that, sapphires are most commonly shaped like hexagonal pyramids or barrels. Either way, the goal of the cut is to enhance the color of the sapphire and include as much of the original weight as possible. 

Carat weight determines the value of the sapphire – as much as any other metric out there. Sapphires can be found in virtually any weight out there – from a single point to large sapphires weighing hundreds of carats. 

For example, it’s far easier to find a large sapphire than it is to find a large ruby – which is something to keep in mind if you are looking for a massive stone for a centerpiece for jewelry. Of course, most sapphires you come across will weigh less than 5 carats, but you can still find larger gems if you need them. 

On the other hand, it is close to impossible to find a large sapphire crystal of the highest quality. Most larger stones are generally commercial-grade and certainly cannot match the quality of a smaller stone, which commonly have higher clarity and better cuts.

Bottom Line

Lastly, there are several ways to determine whether you have a genuine sapphire in your hands or not. All the techniques we have talked about can help you establish whether you have a natural sapphire – including the different types of diamond testers. 

Do keep in mind that diamond testers aren’t 100% accurate, so you should take your gem to a qualified gemologist for them to check it out. Gemologists can be a bit expensive, and they can charge plenty to conduct the report stating the authenticity of the sapphire.

So, if all that seems like too much – grab a diamond tester or order it online if you don’t have it yet, and point to your sapphire crystal!

Related Read: Diamond Vs. White Sapphire: Comparison Guide