Natural vs. Synthetic Diamonds: Spotting the Difference
A diamond is forever, but does it matter if the diamond was recently cultured or one that was produced over millions of years? It may not matter to the heart, but it can at auction.
Natural diamonds are the very definition of elegance and design. Their mystique comes from millions of years of tectonic pressure and powerful volcanic activity. However, there are other much newer options that symbolize everlasting love.
The way a natural diamond reflects natural light is bedazzling. A rainbow of sparkling color is a natural expectation from the exquisitely handcrafted facets of a cut diamond. But what is a diamond, anyway?
Scientifically, any diamond is grown as a tetrahedron, eight triangle-shaped facets that grow from the center outward in a flat square pattern of nothing but hard carbon and tectonic pressure. This pressure deep within the earth’s crust creates the diamond, but volcanic activity “pushes” them closer to within 100 miles of the earth’s surface in kimberlite magma pipes where they are mined, sorted and processed into natural diamond jewelry. The total time from pressurized carbon to “I do” is several million years.
Once natural diamonds were revealed to be nothing more than compressed carbon, by Antoine Lavoisier in 1772, attempts to recreate the natural process to form synthetic diamonds were underway. It would take nearly 200 years and numerous attempts around the world to replicate the process to the point that the resulting product was acceptable for commercial or industrial use.
The most economically feasible process to create synthetic diamonds was developed by General Electric (GE) in the 1950s. The process known as High Pressure and High Temperature (HPHT) begins with a diamond “seed” placed within metallic material which is then subjected to very high pressures and high temperatures. This slowly builds up diamond carbon around the natural seed, somewhat similarly to how a natural pearl germinates, producing one synthetic diamond over a period of about a month.
More recently a Chemical Vapor Deposition (CVD) process was developed that uses low pressure and high temperature. Carbon-based gas such as methane or plasma is pumped into a closed vacuum chamber where a microwave beam then breaks down the carbon molecules. The carbon falls over a panel of multiple diamond seed plates over a month or so slowly building up to create more than one synthetic diamond at a time.
While both processes produce properties that are visually similar to those of a natural diamond, they are so significantly different from each other, and from natural diamonds, that close examination of their atomic structures can easily determine their origin. HPHT diamonds will show a yellow octahedral and blue flat cube structure known as a cuboctahedron, while a CVD synthetic diamond structure features a flat square structure with usually a dark brownish edge of graphite that has to be chemically removed. Neither type displays the octahedron or eight-sided triangle structure of a natural diamond.
How to Quickly Tell
Just looking at a diamond will not necessarily tell you whether it is natural or synthetic. However, there are simple tests that any gemologist can quickly perform to identify the differences through coloration, inclusions, and stress patterns.
According to the Gemological Institute of America (GIA.edu) color variations help to identify diamonds in different ways. While natural diamonds can show some uneven coloration, HPHT synthetic diamonds will show mostly uneven coloration when both are viewed under either magnification or an immersion test. CVD synthetic diamonds show no uneven coloration at all. Under ultraviolet light, natural diamonds will fluoresce blue and yellow; while synthetic diamonds fluoresce in green, yellow green, yellow, orange or red.
Inclusions are an important aspect of diamonds, whether natural or synthetic. Natural diamonds feature bits of dark carbon embedded within the diamond. HPTP synthetic diamonds will also reveal dark inclusions, but these are remnants of the metal flux used in its production. Because they are metallic, they can sometimes be attracted by a handheld magnet, where natural carbon will not. CVD synthetic diamonds are manufactured with no inclusions.
Under magnification, natural diamonds will feature a “strain pattern” usually observed as a crosshatch, mosaic, or of different striations of colors that clearly demonstrate geological pressures evident from its natural creation. Synthetic diamonds show no stress patterns at all.
Other Diamond Types
There are other diamond types that form part of the gem industry classifications as well.
The term melee is used to describe smaller brilliant-cut natural diamonds as well as all small synthetic diamonds. They are used to embellish mountings around larger gems and are categorized as usually weighing about 0.2 carats (about 11mm). Because of their small size and cut in much larger quantities, determining whether they are synthetic or natural is time consuming. A cost-effective test has yet to be devised. A mix of natural and synthetic melee in a commercial packet of 100 diamonds is not unusual.
Once diamonds were able to be replicated in a laboratory setting, a number of diamond-like substitutes were developed. Cubic zirconia, synthetic moissanite, Yttriam Aluminum Garnet (YAG), synthetic spinel, synthetic rutile, and strontium titanate easily replicate the clear brilliance of natural diamond, but at a fraction of the cost. While they have a similar appearance to natural diamonds, they have very different chemical and physical properties that can be readily identified by using a thermal tester, which won’t work with synthetic diamonds.
Neither completely natural nor completely synthetic, a natural diamond can be treated to cover or repair noticeable flaws. Drilling to remove obvious inclusions, filling in cracks, changing or enhancing the natural color through irradiation or even changing the color completely are a few ways to improve the commercial appeal of a natural diamond. Once it is disclosed that it is an enhanced natural diamond, the auction value is much lower than that of a natural diamond.
Values of Diamonds
The value of all diamonds, in any format, is still certified by the 4 Cs: color, carat, cut and clarity, not necessarily in that order. Grading each natural or synthetic diamond is still important, especially for auction and resale.
There are several well-respected diamond-grading certifications available from the American Gem Society (americangemsociety.org), the Gemological Institute of America (gia.com) and the International Gemological Institute (igi.org). While each has their own specialty, they will all evaluate and certify both natural and synthetic diamonds.
Retail prices for synthetic diamonds were higher than natural diamonds only about three years ago, according to the gem industry experts. That’s because manufacturing synthetic diamonds was very high, but innovations have begun to lower the manufacturing cost dramatically so now natural diamonds have a higher retail value overall. But what about resale value?
Natural diamonds may lose at least 50% of their retail value when it comes time to sell to a dealer. Even so, natural diamonds never quite lose their value and, in fact. rise over time at a steady rate, while synthetic diamonds never do, according to the diamond industry.
The resale value of synthetic diamonds isn’t very high if at all. “Lab-created diamonds have no resale value,” says a recent article by Michael Fried titled Lab-Created Diamonds: Prices & Value for diamonds.pro, a consumer-oriented industry website. While that may be true when you want to sell to a dealer, recent auction values show a healthy interest in synthetic diamonds, if not for investment then at least to affordably complement special occasions. “The basic question is, are you willing to sacrifice long-term value for short-term bang for your buck?” asks diamonds.pro.
Another consideration is whether the gem industry is able to confidently identify and heavily restrict “blood or conflict diamonds” that consumers don’t want to acquire. A synthetic diamond just might be a safer alternative to the ones mined and sold by murderous militia.
So, whether your goal is simply to make a sparkling personal statement or you’re planning to make it a lifetime deal after exchanging heartfelt “I do’s,” be assured that there’s a diamond for that.