Want to avoid getting ripped off when you buy your next diamond? This article will outline specific methods for learning whether a diamond was grown in the earth or created in a lab.
How can you tell a lab grown diamond from a natural one? Earth-grown diamonds and lab-created diamonds are visually identical. In fact, even under magnification, the two are completely indistinguishable. The best way to positively identify man made diamonds, is through testing with highly-specialized machines. Magnetic testing can sometimes also be revealing.
What indicators can specialized machines look for? What tests can be done without complex and expensive machinery to identify lab diamonds? Keep reading, we’ll address all that, and more, in the remainder of this article.
Both Man Made Diamonds & Mined Diamonds are Visually Identical
It can’t be overstated that lab grown diamonds have an appearance that’s visibly identical to earth mined diamonds. It’s not just similar (as it is with simulants) it’s identical. That’s because simulants are not actually diamond (they aren’t made entirely of carbon) but man made diamond is.
How hard can it really be to tell the two types of diamonds apart? I recently read a story about a journalist that purchased a synthetic diamond. He took the ring to several well-respected jewelers in the area. After looking at the ring through a loupe and a little small talk, most of the jewelers offered to buy the diamond from him.
The amount they were willing to pay would have represented a significant loss if it had been an earth mined diamond (because they’re significantly more expensive). Since he bought it at a much lower price, as a man made diamond, the offer was only a little below his actual purchase price. They were enthusiastic about buying the ring, until he surprised them with the fact that it was lab-grown. One of the jewelers had owned his store for more than 40 years, and he couldn’t even tell after inspecting the ring carefully.
What does that experience tell you about just how identical synthetic diamonds are to earth grown diamonds? If you can’t rely on a simple visual inspection, what can you do in order to know?
Tests You Can Do on Your Own
We’re going to start with the method that’s the most low tech. This is one that you could easily conduct wherever you need to. Before launching into the technique, I want to quickly remind you that there are two different ways that diamonds are created in laboratories.
HPHT (High Pressure High Temperature): This process is much older, so it’s the most common method of manufacturing today.
CVD (Chemical Vapor Deposition): This newer process uses much less power, and has several other advantages. While it’s currently the less common method of production, that will likely change over time.
1. Grab a Magnet
Believe it or not, man made diamonds produced through the HPHT method often have a trace amount of Iron or Nickel in them. They’re left in a cluster of tiny pin-prick inclusions. Those inclusions are sometimes enough to cause the diamond to be drawn to a magnet.
You’ll need something stronger than your average refrigerator magnet for this. Find a strong Neodymium magnet for best results. You can actually buy a Neodymium magnet in most hardware stores. You can also find them online. The magnet will most likely cost you less than $8 (US). This one from Amazon would be ideal in terms of strength, size, and cost.
There are two ways that you can test magnetic attraction in diamonds:
Touch the magnet directly to the diamond and see if you can lift the gem off the surface that it’s resting on. The strength of the attraction is heavily dependent on where the metallic inclusions are located, relative to the magnet—so you may need to test the magnet on several surfaces around various parts of the diamond before knowing just how attracted it is (or isn’t). You may not notice an attraction on one side of the diamond, simply because it’s far away form a small inclusion that would become evident if the magnet were moved closer.
Float the diamond on something very small and light a bowl of water. Move your magnet very close to the diamond and see if it’s drawn toward the diamond. The float test is a good way to pick up a weaker magnetism. Could even try touching the magnet very gently to the surface of the diamond, and then slowly pulling the magnet away from the diamond. If the diamond follows the magnet, it’s evidence of a magnetic attraction.
What are the weaknesses of magnetic testing?
Not all HPHT diamonds will show noticeable magnetic attraction. Diamonds smaller than .5 carats are less likely to have a magnetic attraction than those that are larger than .5 carats. Even among larger HPHT diamonds, not all will have enough metallic inclusion to make them react to a magnet.
CVD diamonds are formed through entirely different technology, so like earth grown diamonds, they’re magnetically inert (they’re never magnetic).
This means that a strong magnet can identify some portion of lab created HPHT diamonds, but it would also miss a portion (at least 40% of them) according to one study, along with all of the diamonds produced through CVD.
Another difficulty for the average consumer, is that you would need to test each diamond as a loose stone, rather than testing it while it’s mounted in a ring. The reason for that is simple: the metal used in an engagement or wedding ring adds a lot of weight. That added weight would make it nearly impossible for you to lift or move a diamond with a magnet.
2. Look for an Inscription Along the Girdle of the Diamond
Lab Created Diamonds often have an incredibly small inscription on the girdle of the diamond that labels it a Lab Grown. It’s something that’s impossible to see without serious magnification. A standard jeweler’s Loupe is a 10x magnification. You need at least 20x magnification, but more commonly 30x magnification, to be able to see the inscription.
A diamond’s ‘Girdle’ is the widest part of the diamond. The inscription size of the lettering will correlate to the size of the girdle. A very thin girdle will have extra small lettering, which is where the 30x loupe becomes a must have.
Whenever most large grading labs certify a lab grown diamond, they inscribe the girdle, to mark it as lab grown, if that hasn’t already been done. If it’s there, you’ll immediately know that you’re looking at lab grown diamond. If it isn’t there though, that’s not sufficient proof that it’s not lab grown—not all lab grown diamonds are inscribed.
Where do you find a 30x Loupe? You may be able to visit a local jeweler and just borrow theirs for a moment while you’re in their shop, or better yet, you might want to just buy one online, so you can have it handy whenever you might need it. The instrument will likely cost between $10 and $50 depending on the brand and where you buy it. I recommend this one from Amazon. At less than $15, you can’t go wrong with this sturdy 40x magnifier.
Tests That a Jeweler Can Do For You
If you decide not to buy or borrow a loupe, you might just ask a local jeweler to check for an inscription for you. If he has the equipment available, he could potentially run another test for you while you’re there.
3. Use a Type IIa Testing Machine
Diamonds are grouped and classified by ‘type.’ There’s a type I (type 1) and a type II (type 2). They’re then broken down even further in type Ia, type Ib, type IIa, and type IIb. The type that a particular diamond belongs to depends on the trace elements that can be found in it, and the arrangement of those atoms within the diamond. Each type has its own unique tendencies and characteristics.
Type IIa means that there’s very little, if any, nitrogen in the diamond. Nitrogen is the element that gives many natural diamonds and HPHT created diamonds their yellowish hue. Here’s what’s interesting—many lab created diamonds (particularly those created through CVD) belong to type IIa, but very few (less than 2%) earth grown diamonds are type IIa. That means that if your local jeweler has a Type IIa testing machine, you could have a good indication of whether a particular gem is lab created or not.
If it reveals that the gem is type IIa, that doesn’t prove that it’s man made (because again, some earth mined diamonds also fall into that type), but it means there’s a very high probability that it’s man made. Typically, at that point, you would have to send the diamond to one of the large diamond grading laboratories for further testing with highly specialized machines that can give you more definitive results.
If you’re in the market for a Type IIa tester, this is the one that I recommend. It’s a brand with a solid reputation, and Amazon offers it for less than $600!
Tests That a Lab Can Do For You
4. Check Fluorescence
Large labs have access to very expensive machinery that’s specially designed for distinguishing between lab created diamonds and mined diamonds. Some of the machines they have access to could cost as much as $100,000. That’s we’ll outside the range that most jewelers could justify keeping on hand, so when they have a question that their less expensive diamond testing machines can’t answer definitely, they refer it to one to the major labs for further testing.
One machine that’s often used, is the DiamondView which was invented by GIA (Gemological Institute of America). The DiamondView is capable of testing diamonds in a number of ways that help them to accurately determine its origins as either natural or lab grown.
One of the first things they do, is bombard the diamond with special light waves that cause the diamond to fluoresce (or glow). Lab created diamonds tend to fluoresce much more brightly than earth mined diamonds do. That’s one early indicator. Another is the color that each stone returns as the light waves hit it. Natural diamonds are typically blue. Lab Cultured diamonds made through CVD fluoresce in bright orange. Those made through HPHT will fluoresce in a shade of off-blue (like a turquoise) most commonly.
5. Evaluate Growth Patterns
While the diamond is still lit up with Fluorescence and under magnification, the operator of the DiamondView machine will look for growth patterns that are indicative of lab grown diamonds. Diamond actually have a grain in them, that’s much like wood, there are grain patterns that can be evaluated with specialized equipment, that will tell the observer something about how the diamond formed.
Earth-grown diamonds formed deep within the earth over the course of millions of years. Synthetic Diamonds are generally formed in just 6 to 10 weeks. It’s no wonder that they don’t show the exact same graining and grown patterns in both cases. Specific grown patterns that are typical of man made diamonds is a confirming indicator for the operator of the DiamondView machine.
6. Look at Phosphorescence
Finally, the DiamondView operator will turn off the UV waves that they had been using to create Fluorescence, and see if there is an residual light emitted from the diamond (Phosphorescence). Not all diamonds fluoresce. For those that do, the color, duration, and intensity of that light tells them important things about the gem.
Phosphorescence can actually be used to as an indication of where a particular gem is synthetic in some cases, but because precise Phosphorescence qualities are often unique, it can also be used to positively identify diamonds that are lost or stolen.
How Can Everyday People Tell That a Lab-Grown Diamond Wasn’t Earth Grown?
Based on all that’s been discussed here, consider this—if it’s this technical and difficult for professionals to distinguish mined diamonds from lab diamond, your friends, family, and acquaintances have no chance. A lab cultured diamond looks just a beautiful, lasts just as long, but can cost at least 40% less. It’s not imitation diamond, it’s actual diamond, just from a different source. Where’s the downside?
Do Lab Created Diamonds Test as Real Sometimes?
Jewelers could potentially misidentify a diamond with their more limited and inexpensive testing devices. Because of the specialized and sophisticated equipment that grading laboratories have access to today, however, it’s highly unlikely that they would misidentify a lab created stone that they evaluate.
Do Lab Created Diamonds Hold Value?
Jewelry-grade diamonds don’t hold their value well in general, and typically are not sound investments. The resale discount percentage that’s demanded by a buyer is generally consistent for lab grown and mined diamonds. In both cases, a seller will likely fare best by selling directly to another individual.
Does GIA Certify Lab Created Diamonds?
GIA will certify lab-created diamonds. The stone typically can’t be mounted to a ring when graded. The total cost should be $125 or less, depending on the size of the diamond. Smaller diamonds could be less than $70. GIA issues a special report for ‘Synthetic’ Diamonds that uses fewer grading categories.