WHAT ARE LAB-GROWN DIAMONDS?
Lab-grown diamonds are "grown" using technology that mimics nature.
The question we always get asked is: but are they real diamonds?
The answer is yes! Other than their point of origin, lab-grown diamonds are the same as natural diamonds with the same optical, chemical, thermal and physical features as a natural diamond.
"They are real diamonds. They have the same optical, chemical, thermal and physical features as natural diamonds"
- Mathew Hall, Director, Gemological Institute of America (GIA)
Because lab-grown diamonds have the same chemical and optical characteristics as natural diamonds, traditional diamond testers and observations from the naked eye (even a trained one) cannot distinguish lab-grown diamonds from their natural counterparts.
HOW ARE THEY GROWN?
Lab-grown diamonds are created by two methods:​
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High pressure, high temperature (HPHT)
Chemical Vapor Deposition (CVD)
High pressure, high temperature (HPHT)
This method mimics the conditions that form natural diamonds 240km below the earth's surface where carbon dioxide is compressed under extremely high temperatures and pressures.
The process starts with a seed diamond, highly refined graphite carbon and a catalyst consisting of a mixture of metals and powers. The seed is then placed in the centre of the HPHT growth chamber and is heated to temperatures of 1300 to 1600°C with pressures of 1.5 million PSI (pounds per square inch) - roughly the same pressure that would be exerted by a jet plane if balanced on the tip of a person's finger. The carbon melts, changing its atomic structure, and as carbon atoms precipitate onto the seed diamond, the diamond grows. A diamond generally takes three to four weeks to grow.
HPHT is also a process that can be applied to existing diamonds (both natural and lab-grown) to make diamonds more colourless or used to change the colour the diamonds to pink, blue or yellow. A diamond that has been subject to this treatment is known as a "treated" diamond and is disclosed in GIA and IGI reports.
Fun fact: The first ever lab-grown HPHT diamond was produced by General Electric using the belt press process in 1954 under the project codename "project superpressure" but it wasn't until the 1970s that the first gem-quality lab-grown diamond was produced.
Chemical Vapor Deposition (CVD)
Whilst HPHT diamonds mimic what happens within the earth, the CVD method imitates how diamonds form in outer-space - in interstellar gas clouds.
The CVD method places a diamond seed in a vacuum chamber. This chamber is then filled with carbon rich gases (such as methane) and is heated to 900 to 1200°C. The gas turns into a plasma cloud from these extremely high temperatures. An energy source (such as a microwave beam) splits apart the hydrocarbon molecules, causing carbon to precipitate onto the cold diamond seed and grow the diamond. Every few days, the diamonds are removed and have their tops polished to remove any non-diamond carbon before being replaced to grow further. The entire process takes approximately three to four weeks.
"Mined diamonds are a gift of nature whereas man-made diamonds are a gift of human wisdom." - Shanghai Diamond Exchange's President Qiang Lin
TYPE IIA DIAMONDS
Every lab-grown diamond is what is known as a Type IIa diamond. Diamond type is a scientific way of classifying diamonds based on their atomic make-up. Broadly, all diamonds (natural and lab-grown) fall into two categories: Type I and Type II which are then further sub-categorised.
Type I diamonds are the most common amongst natural diamonds. These diamonds contain nitrogen as an impurity. Type IIa diamonds, on the other hand, are almost or entirely devoid of impurities - which in turn ensures a diamond is colourless - and is considered to be the purest form of diamond. Whilst less than 2% of earth-mined diamonds are Type IIa, every colourless lab-grown diamond is classified as Type IIa as lab-grown diamonds are grown in controlled environments.
FAQs
Are lab-grown diamonds graded in the same manner as natural diamonds by GIA and IGI?
Yes - because lab-grown diamonds exhibit the same properties and characteristics as natural diamonds, they are graded in the same manner as natural diamonds by GIA and IGI - using the 4Cs.
Can I pre-determine the 4Cs of a lab-grown diamond?
Despite the more controlled environment in which a lab-grown diamond is grown, diamonds are still at the mercy of science - whether that be billions of years within the earth or within a laboratory. There is no way to guarantee the characteristics of every lab-grown diamond and we can't simply pre-determine what grading characteristics (i.e. the 4Cs) we want for a lab-grown diamond. As a result, each lab-grown diamond remains as unique as each natural diamond.
How are lab-grown diamonds told apart from natural diamonds?
To identify laboratory-grown diamonds, advanced testing at a gemological laboratory is required to identify them with any certainty. The techniques used including analysing a diamond's strain patterns, trace element compositions, inclusions, fluorescence, phosphorescence and more to separate them from natural diamonds. These identifying markers are due to the different ways in which the diamonds are formed or grown.
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GIA and IGI diamond grading certificates will also clearly indicate in their grading reports as well as on the inscriptions of the relevant stone whether a diamond is a lab-grown diamond.
Are lab-grown diamonds the same thing as moissanite or cubic zirconia?
No - they are not the same thing.
Moissanite is a diamond simulant made of silicon carbide. A diamond simulant is a stone that has similar appearance to, but is not, a diamond. Moissanites are nearly as hard as diamonds (natural or lab-grown), scoring 9.25 on the Mohs Hardness Scale (diamonds get a 10!). They also have a higher refractive index which means they exhibit a different kind of brilliance than diamonds - generally of greater intensity and fiery rainbow-coloured flashes. As moissanites exhibit different characteristics, they are graded in a different manner to diamonds.
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Cubic zirconia is also a diamond simulant which is composed of zirconium dioxide. It has a rating of 8.5 on the Mohs Hardness Scale. As a result of that softness, any faceted edges on the stone will generally round out over time from wear. As a result, any fire and spark will also likely dull over time.