First, let's talk about natural diamonds and how they are formed. The processes are quite similar - only one happens underground while the other occurs in a lab.
Diamonds are pure carbon. Geologists theorize that diamonds formed deep within the Earth sometime between 1-3.5 billion years ago when our planet was even hotter than it is today, and up to 155 miles underground...though they have been discovered to have come from 500 miles down! With an enormous amount of heat and pressure, carbon-containing fluids dissolve various minerals and replace them with diamonds. A few years later, a volcano transports the diamonds all the way to the surface.
Natural diamonds can come in different colors! Given how rigid the atomic formation is, it’s actually exceptionally rare for impurities. A few chemicals can contaminate the atomic arrangement and can color the diamond blue (boron), yellow (nitrogen), brown (general defects...chocolate diamonds are not valuable!), green (radiation...is the Hulk made of diamonds?!), and also pink, purple, orange, and red.
Diamonds are also famously hard. Currently diamonds have the highest hardness and thermal conductivity of any known material, which means they hold up to high pressure and stress (me, not so much), and they also do not react to other chemicals. Since the ‘impure’ diamonds and ones with defects are not in high demand, these diamonds are often used for various intensive industrial settings.
Now if you don't want to wait a couple billion years...
There are two main processes labs can use to grow diamonds - High Pressure-High Temperature (HPHT) and Chemical Vapor Deposition (CVD). These processes have been attempted since the 1870’s but it wasn’t until 1954 that the process was solidified (so to speak).
An HPHT diamond begins as a small diamond seed that is placed into carbon and at the bottom of a press. Using one of a couple different manufacturing processes, the seed is exposed to temperatures of more than 1400 degrees Celsius and pressurized to approximately 1.5 million pounds per square inch. The pure carbon melts and starts to form a diamond around the starter seed. It is then carefully cooled to form a pure carbon diamond.
A CVD diamond begins as a thin slice of diamond seed, which is often an HPHT produced diamond. The diamond seed is placed in a sealed chamber and heated to around 800 degrees Celsius. The chamber is filled with a carbon rich-gas, like Methane, and other gases. The gases are ionized into plasma using microwaves, an electron beam, welding torch, or lasers. The ionization breaks the molecular bonds in the gases, and the pure carbon adheres to the diamond seed and slowly crystallizes then bam! You’ve got a diamond.
Somewhat surprisingly, laboratory diamonds do maintain the same properties and qualities as natural ones so they can be used in many different applications. In fact, some synthetic single-crystal diamonds have been found to be harder than any known natural diamond.
Laboratory-grown diamonds are used in many ways; electronics, machining and cutting, optics, and of course...jewelry.
In the gemstone market lab-diamonds popularity has grown 15-20% annually, and continues to expand as environmentally friendly choices become more mainstream, and prices become more competitive. Various jewelry companies have attempted to drive the market back to natural mined diamonds, asserting that the rarity and age is valuable and unique. While they are indeed exceptionally old, they are not rare on the planet.
Long story short...every diamond is made with science!
Why should I buy lab-grown diamonds?
1. There is an immense environmental impact on diamond mining. Land that had once been used for farming has been turned into patches of abandoned mining pits. Soil erosion and deforestation have forced many local populations to relocate, and many of the areas where this mining occurs have created no regulations to avoid any of this.
Laboratory-grown diamonds are not such a drain on Earth's natural resources and are far more conducive to keeping ecosystems and communities intact.
2. Over half of the world's diamonds come from African nations. Unfortunately so many of these populations live in poverty, with some earning less than $1 a day from the mining companies. The risk of environmental accidents, such as landslides or collapses, is extremely high for these miners and they often must work in unsafe conditions without proper tools and safety equipment. It has also been reported that many of the workers are under the age of 16 and have left school to help their families by working in the mines.
Any reputable Laboratory making lab-grown diamonds will adhere to strict Health and Safety Regulations, and so the level of danger for workers is significantly lower. It would also be very unlikely to have child labor in the process (don’t tell my sister that my niece helps me make diamonds).
3. You may have heard about "blood diamonds" or "conflict diamonds" but may not fully understand what this means. Historically, the profits from diamond mines in many countries have been used to finance rebel movements against governments. In reality, this also includes violence and human rights violations against many miners. The Kimberley Process was created in 2003 to try and stop the trade of these diamonds by providing certificates for "conflict-free diamonds". However with limited purview they can only show that the profits are not used to fund rebel movements, and still counterfeit certificates have been found. The narrow definition of conflict has allowed diamonds from mines with violence and human rights violations to obtain Kimberley Process Certifications.
Laboratory-grown diamonds can be supplied with a full disclosure about origin, so you can be sure that a diamond has not come from a conflict zone.
Lab Grown Diamond featured image - By Steve Jurvetson - https://www.flickr.com/photos/jurvetson/156830367/, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=906535