How to Tell if a Diamond is Natural or Lab Created
Two diamonds side by side, both stunning and brilliant. They are equally as hard; they both rate a 10 on the Moh’s scale of hardness. Both diamonds have high clarity ratings, they catch and reflect the light with few visible flaws, and both are well cut and nearly colorless. They are of identical composition, made purely of carbon, and both are of equal carat size. To the naked eye, there would appear to be no major visible discrepancies.
But what if someone were to tell you that one of those diamonds was natural, and the other was a lab-created one? Would you be able to spot the difference?
Don’t knock yourself down if you can’t. With the new technologies in lab-created diamonds, even gemologists are having a hard time telling the difference.
Lab created diamonds are thirty to forty percent cheaper than natural diamonds and are so difficult to distinguish from another with the naked eye that the diamond industry is racing to find new ways and technologies to do just that. In this article we will discuss:
- What Causes the Differences Between Lab-Created and Natural Diamonds?
- Using a Magnifying Glass
- Classification Process (Types)
- Spectroanalysis
- The Difference Between HPHT and Natural Diamonds
- The Difference Between CVD and Natural Diamonds
- Fluorescence
- Laser Inscriptions
- The Breakdown
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What causes the differences between lab-created and natural diamonds?
Organic diamonds form when carbon in the earth’s mantle is subjected to millions of years of conditions of extreme heat and pressure conditions. Lab created diamonds are formed under highly controlled conditions within six to ten weeks in a laboratory.
While the similarities between the lab-created and natural diamond are due largely to their identical chemical composition (pure carbon), these very different growth methods leave their marks. At the same time, it takes powerful equipment to find them.
Using A Magnifying Glass
Speaking of powerful equipment, take the magnifying glass. If you want to differentiate between a natural diamond and a lab-created one, chances are, the first thing you’ll do is put them under a magnifying glass. The magnifying glass is the go-to instrument that jewelers use to tell real gems from fake ones; could it also be used to tell lab-created diamonds from real ones?
The answer is yes, however, the microscope is not always reliable. While a jeweler can use a magnifying glass to spot inclusions that may reveal whether the diamond is organic or not, his observations may not lead him to any definite conclusions. For a closer examination, jewelers rely on spectral analysis, photoluminescence analysis, classification, and or phosphorescence analysis.
In order to understand how these analyses work, a basic understanding of the growth process of LCD and natural diamonds is necessary.
Classification Process (Types)
The formation of natural diamonds requires high pressure and high-temperature conditions. Such conditions only occur in limited zones in the earth’s mantle where temperatures reach at least 2,000 degrees. These zones are known as, “diamond stability zones.”
After the diamonds are formed in these zones, it takes billions of years for volcanic activity to bring them to the earth’s surface. There they cool and form pipes called kimberlite. Kimberlite is the source of most of the planet’s mined diamonds.
As diamonds undergo this process, they attain certain characteristics, many of which separate them from lab-grown diamonds. Because of the high-temperature conditions which they grow under, they generally form octahedral crystals. Lab-grown diamonds, on the other hand, are formed at a lower temperature and display either octahedral or cubic faces. Hence, when a diamond has a cubic face, it can be identified as lab-created.
Natural diamonds also take a longer time to form than lab-created diamonds, which gives them time to form clusters of nitrogen. Synthetic diamonds do not take as much time to form and do not contain these clusters. These nitrogen clusters classify over 95 percent of the naturally grown diamonds as Type Ia. Type Ia diamonds cannot be grown synthetically.
Synthetic diamonds are either Type Ib, Type IIa, or Type IIb. Type Ib diamonds have scattered or isolated nitrogen atoms. Type IIa contains almost no nitrogen, and Type IIb contains boron.
Spectroanalysis
Spectroanalysis refers to the testing conducted on diamonds to determine whether they are natural, lab-created, or simulants by checking for the presence of nitrogen, boron, and hydrogen and determining which class of diamond they belong to, using a spectrometer.
Diamonds consist of a crystalline lattice made of carbon atoms. When they form, the high-pressure conditions allow other trace elements to leak in. Hydrogen, boron, and nitrogen are all trace elements that are easily identifiable along the spectrum.
Identifying a real diamond is relatively simple. In the case of a real diamond, nitrogen is the most important trace element in its classification. The presence of nitrogen clusters identifies a diamond as Type Ia natural diamond. When hydrogen and boron are detected, it indicates that the diamond is lab-created.
Determining whether a diamond is synthetic or not is a little more difficult. Treatments done in laboratories can significantly enhance the appearance of lab-created diamonds and make identifying them one of the biggest challenges to gemologists today.
In spectroanalysis, the spectrometer displays infrared peaks corresponding to the nitrogen and other elements that can be used to prove the origin of the stone, taking some of the guesswork out of it for gemologists. However, with the increasing quality of lab-created diamonds, there is still a lot of guesswork to be done.
The Difference Between HPHT Diamonds and Natural Diamonds
The HPHT method is the original process used to grow diamonds. It was first introduced to the market by General Electric in the 1950’s. In this process, a diamond seed is placed in a small capsule in a high-pressure apparatus. The starting material dissolves in a molten metal flux, producing the seed needed to form the crystal of the synthetic diamond. This crystallization takes place over a period of several weeks.
The easiest and most reliable way of separating the HPHT diamond from the real diamond is by its shape. Because the HPHT and natural diamond are grown using different processes, the shapes they form into differ as well. While both natural and HPHT diamonds form into an octahedral shape, diamonds grown using the HPHT method are more commonly identified by their cubic shape.
Another way of distinguishing the HPHT diamond from the natural one is by its visual features. HPHT diamonds can be identified by their color distribution, graining patterns, cross shaping, and typical presence of dark flux inclusions.
They tend to be brownish in color. Most are Type IIb, in contrast to the Type Ia classification of the natural diamond.
The Difference Between CVD Diamonds and Natural Diamonds
In the CVD method, diamonds are placed in a vacuum chamber with a carbon-containing gas, such as methane. When a source of energy is applied, the methane molecules are broken down, and the carbon atoms attach themselves to a diamond seed plate. In a few weeks time, crystallization occurs.
Although many of the CVD crystals formed are greyish brown, they can be heat treated by changing the gases in the growth chamber to remove this undesirable hue. Because the vacuum chamber contains only carbon and some hydrogen, colorless diamonds can be formed. Additionally, if nitrogen and boron are added to the mixture, pink, blue, and yellow diamonds could be produced.
As a result of this heat treatment, many of the signature features of synthetic diamonds are masked, making them difficult to distinguish from a natural diamond. CVD diamonds exhibit an even coloration and are relative, if not totally free of inclusions. CVD diamonds are also of the IIA variety, which means they are made of a purer diamond seed which can improve the color and increase growth rates.
With these improvements, the CVD diamonds are posing the biggest challenge to gemologists looking to distinguish the natural diamonds from the lab-grown ones.
Fluorescence
One of the more sophisticated ways of discerning a lab-created diamond is by using a Diamond View Machine to examine a diamond’s fluorescence.
A diamond’s fluorescence refers to the soft glow it gives off in ultraviolet light.
The fluorescence of lab diamonds is often stronger than natural diamonds and displays a distinctive pattern when exposed to UV light. Some synthetic diamonds may not display fluorescence at all.
When put under a Diamond View machine, HPHT diamonds show a cross-shaped fluorescent pattern on the crown or pavilion of the stone. CVD diamonds show a striated pattern when viewed through the pavilion facets. Natural diamonds can exhibit a variety of patterns.
The fluorescent colors emitted by the stones also differ. Colors exhibited by the synthetic diamonds are typically green, red, yellow, yellow-green, or orange, compared with the blue of the natural diamond.
When the ultraviolet light is removed, the synthetic diamond will continue to phosphoresce for up to a minute or more; a natural diamond will cease to fluoresce as soon as the light is turned off. This is yet another way in which the two diamonds differ.
Laser Inscriptions
Laser inscriptions don’t need sophisticated machinery to spot them. Mother Nature does not put her signature on her diamonds, but some synthetic diamond companies do. One of the most obvious ways to distinguish a naturally grown diamond from a lab-grown is a tiny laser inscription on the diamond with the words, “Lab-Grown.”
The Breakdown
In a nutshell, the differences between the synthetic and lab-created diamonds are few and far between. With the way technology is advancing, they’re not on track to get much bigger any sooner.
As of now, there are several characteristics that distinguish natural diamonds from lab-created diamonds, and several characteristics that distinguish CVD from HPHT diamonds. Here are a few ways to define traits of the CVD and HPHT diamonds.
HPHT
- Uneven color distribution
- Unusual fluorescence
- Metallic flux inclusions
- Graining patterns
- Occasional phosphorescence
- Possible inscription
- Fluorescent color patterns
CVD
- Unusual color distribution
- Fluorescent color patterns
- Occasional phosphorescence
- Banded Strain Patterns
- Possible laser inscription
- Gemologists use many kinds of gem testing equipment to reveal these characteristics, including a refractometer, a binocular microscope, a polariscope, and an ultraviolet fluorescent lamp. You only have your naked eyes. As for the two diamonds, we think the only difference you should be worried about is the price.
Now that you read the article, what do you think? Is it worth it to go to all these measures to tell the difference between a lab diamond and a natural diamond or should you just look at each diamond individually?