Natural diamonds, lab-grown diamonds, and fake diamonds: what’s the difference?
The Rare Natural Diamond
The word “diamond” comes from the Greek word “Adámas” meaning “indestructible”. This refers to the great strength and durability of the stone. Diamonds are four times harder than any mineral on the earth.
Uncut natural diamond crystal
When you look into a natural diamond you are staring into billions of years. This is because the natural diamonds used in jewellery were formed before land plants and animals even appeared on our planet.
Diamonds are incredibly rare. They are the purest form of transparent carbon that has become crystallized in an isotropic 3D form, under extreme conditions of temperature and pressure. This occurs many kilometres below the surface of our planet. Diamond deposits tend to occur in specific areas or “diamond stability zones” within the mantle of the earth.
These zones are not present globally, so no one knows exactly where diamond deposits exist. Volcanic activity must carry the diamond deposits from the fiery mantle through the earth’s crust.
Natural diamonds can also be formed by other processes:
- Sometimes an oceanic plate slowly collides with a continental plate, creating the pressure and temperature for a diamond to form. These diamonds are small and not commercially viable.
- Asteroids striking the earth can produce intense pressures and temperatures to make a diamond. Such diamonds are scarce and are not generally available for purchase.
- Diamonds can be present in meteorites. These rare and tiny diamonds are the result of collisions between matter in outer space.
A natural diamond is precious because of its hardiness and sparkle, and because of its rarity, energy and age. A natural diamond has to be extremely well cut and polished to have maximum value.
Because of their rarity, natural diamonds will always retain their value and even grow in value, making them great investments.
Laboratory grown diamonds
Synthetic diamonds grown in laboratories have been marketed recently as if they were new inventions, but lab diamonds have been around since the 1950s. Early lab-made diamonds were mainly used for technical and engineering purposes. Nowadays, most of the diamonds used for industrial procedures are cultivated in labs, but man-made diamonds have been sold in the jewellery trade for many decades.
There are two main techniques for the synthesis of a cultivated diamond:
- the high-pressure high-temperature (HPHT) method,
- and the chemical vapour deposition (CVD) crystal formation method.
Both require a “diamond seed”, which is the crystal that will form the basis of growing the diamond. This crystal can be taken from a natural diamond or a synthetic diamond.
The HPHT method was first used by the General Electric Company in 1955 to produce synthetic diamonds in a high-pressure reactor chamber. Until recently, this process of creating diamonds was limited to making diamonds for industrial use. In the 1990s technological advances made it possible to produce HPHT diamonds that were large enough, and of a high enough quality, to be marketed for jewellery. In the early years of their production, HPTP-produced synthetics were shades of orange and yellow, but now colourless and blue stones are more common. When cut, HPHT cut stones can be larger than 10 carats, and smaller HPHT synthetics are being mass-produced in China.
In the HPHT process, graphite or diamond powder is placed into a reactor chamber on top of the diamond seed, and a metal catalyst is added for growth. The chamber imitates the way that diamonds are created under the earth, subjecting carbon to the necessary high pressures and temperatures.
The CVD method is very different from natural diamond formation. This process was supposedly patented in the 1950s but it was only in the 1980s that scientists mastered how to create CVD diamonds. In the CVD manufacturing system, hydrocarbon gas and hydrogen are placed into a vacuum chamber at very low pressures and then heated. Under these conditions, the hydrogen converts to atomic hydrogen, and this promotes diamond formation. The activated carbon-hydrogen atoms in the chamber attached to the diamond seed, bonding with its carbon atoms, and replicating the crystal structure of the seed. Though the CVD system can produce thick growth vertically, laterally the final gemstone can only be as wide as the seed diameter. This means that the size of the CVD manufactured diamond is dependent on the size of the seed.
Early experiments with growing diamonds in CVD chambers enabled the production of only one synthetic diamond in one manufacturing cycle. Nowadays CVD processes are capable of growing 50 or more diamonds at a time, and this capacity is expected to increase in the future.
Growing a diamond in a laboratory usually takes a matter of weeks. After the diamond has reached its ideal growth size, it is cut and polished in the same way as a natural diamond.
Synthetic diamonds can be easily identified by their blue colour in the De Beers DiamondView, which was designed to detect synthetic diamonds.
The DiamondView reveals distinctive fluorescence patterns in HPHT synthetics, as these diamonds display magnetism and phosphorescence reactivity that does not occur in similarly coloured natural diamonds. The GIA Gem Trade Lab has reported that CVD diamonds tend to have high red fluorescence under UV light.
A diamond’s GIA certificate will reveal whether the diamond is “laboratory-grown” or natural.
Are laboratory diamonds worth it?
Synthetic diamonds are cheaper than natural diamonds by up to 30%. But it is not clear whether they will retain their value in the future, as they are now being mass-produced, and rarity is directly related to an item retaining its value over time.
Consider the example of man-made rubies and sapphires:
Laboratory made rubies have been around since the late 19th century after Auguste Verneuil in France used the Flame Fusion process to synthesise ruby particles. Powdered alumina and chromium were fused with corundum using an oxygen-hydrogen torch at 2000 degrees Celsius. Similarly, Carrol Chatham from the USA created sapphires in a lab, in the 1930s using Flame Fusion with corundum, iron and titanium.
Like diamonds, man-made rubies and sapphires are extremely hard and resilient and therefore have industrial uses. They have also been marketed for jewellery. When they first became used for this latter purpose the price of natural sapphires and rubies suffered.
However, in time a natural sapphire gemstone came to be far more valuable than a laboratory-grown sapphire. A natural sapphire can be up to 1000 times more valuable than a laboratory-made stone of similar size, colour, and properties. You can currently purchase a 1ct man-made sapphire for around 5 USD, while a top-quality 1ct sapphire will cost about 5000 USD. This is a clear indication that lab-grown diamonds will have little value in years to come. Natural diamonds will always hold their value and sparkle.
There are two types of fake diamonds, namely cubic zirconia and moissanite. Both are synthetic or man-made. They look like diamonds but are not made from pure carbon. Most jewellers can tell the difference just by just looking.
1. Cubic zirconia:
– Cubic zirconia (CZ) is the cubic crystalline form of zirconium dioxide (ZrO2). It was discovered in the 1930s as an inclusion within a natural zircon crystal. The cubic zirconia in commercial jewellery, however, is synthetic.
Laboratory made cubic zirconia, which has been on the market since 1976, is forged from zirconium oxide powders mixed with calcium and magnesium. It can be made to resemble a colourless diamond and fancy coloured diamonds. Cubic zirconia can also imitate the cut of any real diamond, from cushion cut to princess cut diamonds.
Compared to real diamonds cubic zirconia is inexpensive, and for this reason, it can seem like a good alternative for a diamond engagement ring. But although it looks similar to a real diamond, cubic zirconia has no real value. It costs about 0.2 USD for 1ct.
Cubic zirconia has a lower refractive index than a diamond, so it will shine less and not produce the wonderful shimmering radiance of a real diamond.
Cubic zirconia tends to emit warm orange hues and looks cheap.
It is also not nearly as hard or resilient as a diamond. A diamond will last you a lifetime and beyond to become a family heirloom, but after two years a cubic zirconia will need to be replaced as it will become scratched and cloudy with normal wear and tear. For this reason, it is not ideal in an engagement ring.
2. Synthetic moissanite
In 1998, moissanite became a major competitor to cubic zirconia in the market of fake diamonds. Like cubic zirconia, moissanite can be found naturally, but this is extremely rare, and all commercially available moissanite is synthetic.
In its natural form, moissanite is found as tiny crystals within meteorites. It was discovered in 1893 by French scientist Henri Moissan who found microscopic particles of the material in a meteor crater in Arizona. At first, he thought these crystals were diamonds but found out that they were made of silicon carbide, a compound that had already been synthesised in the 19th century.
In the laboratory, moissanite is created as a single crystal out of silicon and carbon by a patented technology that grows the fake diamond within two to three months.
Because the technology is patented, only one company in the world, Charles & Colvard, is technically allowed to make moissanite, though other companies make the same type of faux diamond and sell it under different trademarked names.
Moissanite is superior to cubic zirconia in hardness and resilience. Being made partly of carbon, moissanite is closer than cubic zirconia to the structure of a real diamond, which is pure carbon.
Unlike cubic zirconia, which is extremely cheap, moissanite costs about 10% the price of a diamond of a similar size and shape.
Yet Moissanite is not as hard or resilient as a real diamond, and moissanite is not colourless. Until 2015, the best you could get on the scale of colour for a moissanite was the equivalent of a diamond graded “K” for colour. Recently Charles & Colvard have developed moissanite that is closer to an “F” coloured diamond.
Fire and ice: Moissanite has a double refractive ability, which technically makes it more sparkly than a cubic zirconia or even a real diamond. But the light emitted is more of a rainbow. It exhibits “fire”, whereas a real diamond radiates both fire and ice through colourful flashes interspersed with brilliant white scintillation. The rainbow light emitted by moissanite can make the “stone” look fake and plastic.
For a diamond engagement ring, the main problem with moissanite is that it is not a diamond. People tend to look down on fake diamonds when they are used for something as serious as a betrothal.
Our sales team at Cape Diamonds can talk you through the process of choosing a perfect conflict-free, GIA-certified, natural, earth-made diamond for your engagement ring, at a price that will suit your budget.
Remember that we offer to beat any other quote.