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Natural vs. Synthetic Diamonds: Spotting the Difference

This lovely set of natural diamond earrings with a total carat weight of 2.40 carats set in 14K white gold sold recently for $10,400. A similar set of synthetic earrings in the same setting would sparkle similarly but sell for a fraction of that price. Image courtesy: Estate Jewelry Auctioneers and LiveAuctioneers

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.

Natural Diamonds

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.

This sterling silver with large 2.25 carat synthetic white diamond pendant sold recently for $50 , considerably less than if it had been a natural diamond. Yet from a distance, its cut, carat, clarity and sparkle rivals that of a natural diamond. Image courtesy Greenwich Auction and LiveAuctioneers

Synthetic Diamonds

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.

Within a large collection of smaller diamond stones such as are seen in this lot weighing 10 carats, there might be a mix of natural and synthetic diamonds, especially if the stones are 0.2 carats (11 mm) known as melee. There is no standardized test to sort out the difference just yet. Auction price: $1,000. Image courtesy: Jasper52 and LiveAuctioneers

Diamond Melee  

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.

Diamond Simulant

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.

These 10K gold earrings are set with a quarter-carat (total weight) of irradiated blue diamonds. The “enhanced” melee diamonds are still diamonds, but the change in color reduces their overall value. They sold for $295. Image courtesy World Jewelry Auctions and LiveAuctioneers

Diamond Enhancement

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.

Diamonds: In Living Color

While most are familiar with the fiery sparkle of clear, colorless diamonds, the coveted gemstones actually occur in all colors of the rainbow.

Diamonds are the product of time and nature. It took an average of two billion years for highly compressed carbon, 90 to 500 miles underground, to form hardened crystals known as allotropes. Then, sometime within the last 100 million years or so, volcanic eruptions deep within the Earth deposited the highly structured crystals in vertical “pipes” of igneous kimberlite. Commercial miners have been extracting diamonds from kimberlite ever since the first major diamond discoveries in South Africa, in the mid-19th century. 

Your diamond ring or pendant tells a great story of creation from stone to symbol of love as it dazzles and throws off light in every direction. But pass a light through a clear, colorless diamond just right and you’ll discover that it reflects all the colors of the rainbow.

Pick a color, any color, and it can probably be seen in a diamond. From the colorless to the darkest black, with variations of color in between, diamonds are hued according to the impurity of chemicals found in the Earth itself.

Colorless diamonds, for example, have no visible impurity apart from small specks of black carbon called inclusions. However, an additional natural chemical impurity and how the atoms are distributed (called “lattices”) can change the colorless into a palette of colorful options. According to the diamond industry, there are 27 different official variations of diamond colors.

A GIA-certified fancy yellow diamond weighing 4.17 carats in a cushion-modified brilliant cut fluoresces a gentle yellow hue. It sold for $50,000 in September 2019. 
Image courtesy Kissing Auctions and LiveAuctioneers

What is a diamond color?

In 1953, the Gemological Institute of America (http://www.gia.com) classified the rarity of polished diamonds based on the now iconic four ‘C’s: carat (weight), how it’s cut, and its clarity. Most diamonds made into pendants, rings, bracelets, earrings, necklaces, and brooches are clear. But even colorless diamonds usually display some subtle shade of color. The more colorless, the more valuable a diamond is per carat. 

To determine a diamond color, a standard grading system was developed that classified an individual polished diamond according to the shade of color ranging from D (colorless) to Z (light color). The closer to grade D, the more colorless it is and the more valuable. How is the color measured? A loose, cut diamond is exposed to ultraviolet light, which measures its “fluorescence,” or the light a diamond gives off. A yellow fluorescence is less desirable than a blue fluorescence, for example, which affects the final value of the cut diamond.

So with all that in mind, here’s a primer on diamond colors, based on information from the Diamond Manufacturers and Importers Association (http://www.dmia.net). 

Red diamonds certified as a “D,” the highest color standard, would be worth millions per carat as they are the rarest diamonds mined. This fancy red 2-carat example is at the far end of the color standard near the “S” range and sold for $37,500 in March 2014. 
Image courtesy Vancouver Island Art Auction and LiveAuctioneers

The fancy color diamonds

Clear 

These are not actually clear or translucent, according to the diamond industry. They are classified as white diamonds, usually free of additional impurities other than pure carbon called inclusions, which determine its final value. 

Brown

Curiously enough, brown diamonds are the most common color of diamonds overall. The lattices reflect the darker brown color. They don’t have the brilliance of the more pastel varieties and were mostly intended for industrial use. However, these ‘chocolate’ diamonds are gaining gaining interest beyond their industrial applications and are being set as a distinctive counterpoint to the more reflective diamonds in jewelry. 

Orange

An orange diamond gets its appearance from its high concentration of isolated nitrogen. While pure orange color is very rare, those that have secondary colors such as yellow, brown or even pink are more commonly seen. 

Yellow

Like orange diamonds, yellow diamonds contain more of the nitrogen atom that fluorescences yellow than other diamonds. The brighter the shade, the more valuable the stone. Lighter shades of yellow that also show shades of green, yellow or even brown are more readily available.

According to diamond sites, values for diamonds in fancy colors can range from thousands of dollars a carat to nearly $50,000 a carat for the very intense color range. 

 

One of the rarer diamond colors, this 3.5 carat fancy blue, marquis-cut diamond whose “…clarity may be potentially internally flawless…,” according to the auction-catalog description, is set off by a platinum band and baguette diamonds along the band. The ring sold for $1.4 million (hammer price) in April 2013.

 

The rarest diamonds

Blue and pink are among the rarest diamond colors. Such stones can sell at auction for millions of dollars per carat, depending on the vibrancy of its color.

Other diamonds that rarely appear at auction are gray, purple and green. Green diamonds, for example, are formed from natural exposure to radiation and the formation of lattices. Once found, these diamonds are usually professionally cut and retained as an investment rather than being set into jewelry. 

Black diamonds have an overabundance of graphite that makes the stone rather opaque and particularly rare in a completely dark black color. 

These color diamonds can range in value from $10,000 to several times that per carat depending on the vibrancy or absence of other colors when placed under UV light. 

The most rare of any diamond shade is the red diamond. A pure-red diamond can auction for millions of dollars per carat. Like brown diamonds, the red diamond’s color comes from its lattice construction and not necessarily from a chemical impurity, but is very difficult to find a diamond that is pure red.  

This more-standard “white” diamond shows brilliantly when cut into a heart shape and set in white gold. Its total weight is 1.65 carats. Sold for $4,600 in March 2019.
Image courtesy Great Deal Auctions and LiveAuctioneers

An investment that sparkles

Diamonds are considered a great addition to an investment portfolio. They hold their value, even during inflationary periods, don’t take up a lot of room, and are portable. Yet, diamonds are one of the few investments that can be appreciated aesthetically, as jewelry, rings, pendants, brooches or watch adornments. And they make a lasting personal connection when given as gifts on special occasions. That’s hard to do with stocks and bonds.

Diamonds and ethics

Diamonds are mined in different ways. The Kimberley Process Certification Scheme (KPCS) is the international standard for overseeing the import and export of diamonds to severely restrict “conflict” or “blood” diamonds from reaching the end consumer. This terminology refers to diamonds mined in a war zone and sold to finance an insurgency, an invading army’s war efforts, or a warlord’s activity. While the KPCS isn’t always successful, diamonds exported to the United States, the largest diamond market, it has strengthened the diamond trade’s efforts to keep “blood diamonds” out of the marketplace. A retailer should have the certification available to prove a diamond’s source, if asked.

From millions of years as pressurized carbon to a dazzling accessory, diamonds really are “forever.”