Diamonds have long been admired for their beauty, rarity, and strength. But not all diamonds are formed the same way. While natural diamonds were created deep within the Earth billions of years ago, synthetic diamonds are made by humans using advanced technology.
Natural Diamonds
Natural diamonds are formed under extreme heat and pressure about 150–200 km deep beneath the Earth’s surface, in the base of ancient, stable parts of continents. Some even come from superdeep levels — as deep as 300–800 km, which is far deeper than almost any other natural rock we find.
Since they form so deep and do not survive the oxidizing conditions of common basaltic volcanism, we cannot access them until rare kimberlite eruptions bring them to the surface.
The oldest known diamonds, found at the Diavik and Ekati mines in Canada, are 3.5 to 3.3 billion years old — meaning they formed before oxygen appeared in Earth’s atmosphere.
Scientists have also found that most diamonds are made almost entirely of carbon, with only tiny traces of nitrogen, boron, or other elements. With the latest analytical tools, researchers can now detect even smaller amounts of these trace elements, helping them understand how and where different diamonds formed deep underground.
Your diamond might also carry a story that scientists have yet to discover.
Synthetic Diamonds
Synthetic diamonds are made in a factory within a few weeks, using two main methods — High Pressure High Temperature (HPHT) and Chemical Vapour Deposition (CVD).
HPHT diamonds are created by imitating the natural conditions of high pressure and high temperature that exist deep inside the Earth, but in a controlled machine environment.
CVD diamonds are formed in a vacuum chamber, where a microwave beam causes carbon to precipitate out of a plasma cloud and slowly deposit onto a small diamond seed crystal, layer by layer.
Both methods produce diamonds with the same carbon crystal structure, but since they are created by people, not by nature, they do not carry the age, rarity, or geological story that make natural diamonds truly special.
Optical and Physical Differences
While synthetic and natural diamonds look very similar, experts can still tell them apart using various tests.
Phosphorescence
Some synthetic diamonds show a glowing effect under shortwave ultraviolet (UV) light that lasts a few seconds after the light is turned off — a feature rarely seen in natural diamonds.
Cross-Polarized Filter Test
When viewed under a cross-polarized filter, natural diamonds often show irregular internal stress patterns, appearing in colourful patches or stripes. Synthetic diamonds, especially CVD types, usually show uniform or banded stress patterns, which can help experts identify them.
Diamond Type Classification
Almost all near-colourless synthetic diamonds are Type IIa, meaning they contain almost no nitrogen impurities. In contrast, about 98% of near- or colourless natural diamonds are Type I, which do contain trace amounts of nitrogen.
Because this difference cannot be seen by eye, experts use advanced screening instruments such as spectrometers to determine the diamond type before further testing if it is suspected to be synthetic.
Conclusion
Both natural and synthetic diamonds are beautiful forms of carbon crystal. Synthetic ones are more accessible and affordable, while natural diamonds carry billions of years of Earth’s history within them.
For those who value origin, rarity, and the story of time, natural diamonds remain unmatched — a true wonder of nature that technology can imitate, but never replace.
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