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Earth-mined vs Lab-grown Diamonds



To the naked eye, there is no difference between earth-mined and lab-grown diamonds—even seasoned jewelers would tell you that. What’s more, both types of diamonds are made of the same material (carbon atoms), and have a nearly identical chemical composition.

To tell the difference, the gemstone must be authenticated using diamond and moissanite testers and diamond verification instruments® or other specialised gemological instruments. But no matter how alike they look or that they share the same chemical properties, natural and man-made diamonds differ in price, resale value, and appeal to consumers.  

Here’s a 3-minute read on diamonds—the world’s most popular and symbolic of gemstones—whether mined from the earth or made in a lab. 

Lab-grown Diamonds

Man-made, lab-created, cultured…however it’s called, if a diamond is engineered in a laboratory and not mined from the earth, then it is categorised as lab-grown. 

Creating lab-grown diamonds entail recreating the “origin conditions” of natural diamonds through advanced technology, but fast-forwarding the process. The highly controlled laboratory conditions mimic the environment that allowed natural diamonds to develop. But lab-grown diamonds don’t take millions of years to form and don’t require mining to harvest. 

Lab-grown diamonds are made of the same carbon atoms as that of natural diamonds, and similar chemical properties and crystal structure. They are as strong as natural diamonds, with a hardness of 10 on the Mohs scale. But while it took 1 billion to 3 billion years for natural diamonds to form, lab-grown diamonds can be developed in a matter of weeks.

For anyone who is investing in precious jewels, it’s critical to use a diamond tester on every piece of jewelry that passes through your hands. Even the most seasoned gemologist would find it nearly impossible to differentiate lab-grown from natural diamonds. 

To distinguish colorless diamonds from CVD/HPHT lab-grown diamonds or moissanites from D to J color, we recommend ARI by Presidium, a Presidium Diamond Verification Instrument® (registered trademark of Presidium Instruments Pte Ltd.) It works well with the Presidium Diamond Mate Tester (PDMT-A), for loose and mounted stones as small as 0.02ct. 

The Presidium Diamond Mate Tester (PDMT) is a complementary product to ARI, for further distinguishing diamond simulants such as colorless sapphire and cubic zirconia from unknown colorless stones. As a first step, users can test an unknown colorless stone using the PDMT-A. Upon a positive "Diamond" reading, users can then use ARI to test if the stone is a natural diamond, potential lab-grown CVD/HPHT diamond, or moissanite.

Earth-mined Diamonds

Natural diamonds were formed within the earth’s mantle, at least 150,000 meters below the surface. Diamonds organically developed under intense heat (up to 1,300 degrees Celsius) and immense pressure (50,000 times stronger than that of the earth’s surface).

It took billions of years  for the carbon atoms to crystallise and form the diamond’s unique crystal structure (diamond cubic). Earth-mined diamonds are extracted from million-year-old igneous rocks (lamproites and kimberlites) that were pushed to the surface through volcanic eruptions.

Natural diamonds are not man-made, but rather extracted through mining. Accessing primary deposits of diamonds entails pit mining or underground mining; alluvial mining is for secondary deposits. While the bulk of natural diamond deposits are mined on land, marine mining is also applied for extracting diamonds underwater, beneath the seabed.

Another PRESIDIUM DIAMOND VERIFICATION INSTRUMENT® is the Synthetic Diamond Screener II (SDS II), which is used to distinguish Type IIa colorless diamonds from natural Type Ia colorless diamonds by measuring the stones' UV light transmittance. The unit gives clear and accurate results within two seconds and is suitable for both loose and mounted stones with an open-backed setting,  as small as 0.02ct. 

We recommend using the Presidium Multi Tester III first to determine if an unknown colorless stone is a diamond before testing it with the SDS II to check if it is a natural or Type IIa diamond (CVD/HPHT diamond). The SDS II has been ASSURE TESTED by an independent third party through ASSURE program and achieved 100% Laboratory-Grown Diamond Referral Rate. 

Diamond Simulants

Diamond simulants are created from materials that are naturally occurring, fabricated by humans, or a combination of both. The most common diamond simulants are synthetic cubic zirconia, synthetic moissanite, gadolinium gallium garnet, and yttrium aluminum garnet (YAG). They may resemble earth-mined and lab-grown diamonds, but the similarities end there.   

For instance, cubic zirconia is in no way as hard as diamonds. And while you can’t tell the difference between lab-grown and earth-mined just by looking at it, it’s not as  difficult to do that with cubic zirconia. 

Meanwhile, moissanite, another type of diamond simulant, comes close to a diamond in hardness (9 to 9.5 on Mohs scale, compared to the perfect 10 of a diamond). But despite the striking resemblance, moissanites have “too much sparkle,” as some jewelers put it. A diamond’s “brilliance level” has a 2.65 refractive index while moissanites registers at 2.69. 

Lab-grown diamonds share the same material properties as natural or earth-mined diamonds. But the physical and chemical composition of diamond simulants are vastly different.  Although produced in a laboratory, diamond simulants are not made up of carbon atoms, unlike lab-grown diamonds.

The Presidium Multi Tester III (PMUT III) can be used to check if a stone is a diamond or a diamond simulant. It can instantly distinguish natural colorless diamonds as small as 0.02ct and differentiate them from moissanites, cubic zirconia, colorless sapphire, and other diamond simulants based on their thermal and electrical properties.

Moreover, thermoelectric or thermoelectrical diamond testers can detect diamonds, moissanites, and simulants instantly. One such instrument is the lightweight and portable Adamas by Presidium, for authenticating colorless diamonds as small as 0.01 carats.

An industry forerunner, Adamas diamond tester is the world’s first diamond and moissanite tester with a replaceable tip, and a micro probe tip. In the long run, a worn-out or damaged probe can simply be replaced; you don’t have to buy a new diamond tester.


What is ‘Real’?

According to the revised jewelry guidelines of the US Federal Trade Commission (FTC), man-made diamonds cannot be called artificial or synthetic. As per the FTC's new definition, a diamond is "a mineral consisting essentially of pure carbon crystallized in the isometric system" and since both mined and man-made diamonds "have essentially the same optical, physical, and chemical properties as mined diamonds. Thus, they are diamonds."

As for diamond simulants, the  FTC says, "many consumers mistakenly believe 'synthetic' means an artificial product such as cubic zirconia, which lacks a diamond’s optical, physical, and chemical properties."

Mined diamonds contain trace amounts of nitrogen, which are absent in man-made diamonds—the only differentiating factor. Man-made diamonds are graded the same way as mined diamonds, by way of the 4Cs: Cut, Clarity, Color, and Carat. However, the GIA does not give certifications for lab-grown diamonds.

As such, it would be misleading for diamond sellers or marketers to say that man-made diamonds are synthetic, fake, or "not real" because lab-grown diamonds are actual diamonds. They are as "real" as earth-mined diamonds in terms of carbon-based chemical makeup.

Why PRESIDIUM for Diamond Testers and Industry-trusted Gemological Instruments