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Laboratory-grown diamonds

CVD versus HPHT, value and sustainability


We do not sell laboratory-grown diamonds. The purpose of this page is to provide information about them. No purchase decision is wrong, as long as the buyer is fully informed.

- Article by John Pollard, Crafted by Infinity diamonds

Are they real?

Yes. Laboratory-grown diamonds are real. They are not simulants like CZ and moissanite. They are not "fakes." Aside from subtle carbon distinctions, they are chemically identical to natural diamonds.

However, unlike earth-mined diamonds which formed beneath the planet's crust over billions of years, they are grown in factories using sophisticated methods of chemical synthesis over a period of 1-4 weeks.

Are they eco-friendly?

Not according to the FTC. There is controversy surrounding sustainability, environmental impact and power consumption. FTC warnings have been issued regarding "eco-friendly" and "sustainable" claims but sales promotions remain largely unregulated. There is also a value component which is important for consumers to understand before buying (addressed below).

Do they look natural?

HPHT-productions are physically identical to natural diamonds but may have distinctive undertone and metallic inclusions. CVD-productions are physically different than natural diamonds, with optical differences in refractive index and subsequent performance.

To understand those differences it is necessary to outline the different production methods.

CVD process (chemical vapor deposition)

The CVD process releases carbon atoms from plasma. It involves superheating hydrocarbon gas in a vacuum to between 3,000-4,000C, at which point the carbon atoms begin to separate from their molecular bonds. Those atoms descend and land on a flat wafer of previously grown HPHT synthetic diamond and grow in vertical layers. The substrate is square for jewelry applications but it can vary for other uses.

CVD process. Courtesy, Element Six

Optical tendencies

  1. CVD produces a brown undertone. This has been reduced as technology advances but is still very present in the mainstream.
  2. The CVD process does not imitate the growth of natural diamonds so they are not “physically identical." CVD growth is like carbon rain falling onto the base substrate, growing vertically in parallel layers. A by-product of this growing process is layers of stria which create variation in the refractive index. That reduces visible fire and brilliance. CVD diamonds are typically less ‘crisp’ in performance, even when cut well. Under spotlighting this presents like a polishing problem. but it’s a systemic issue attributable to the material.
  3. Some CVD producers use an additional HPHT annealing process to further bleach their output. This reduces the presence of undertone by converting the heavier brown to pink or grey, pictured below.

CVD rough material. Courtesy SoniCVD

HPHT process (high-pressure, high-temperature) 

Essentially, HPHT replicates the natural conditions under which diamonds formed 100 miles below the surface due to subduction. A carbon source, a diamond seed and a metallic catalyst go into an octahedral cell. The cell is placed into a massive mechanical press where the contents are heated near 1,500 C and subjected to staggering pressure. The melting metal dissolves the carbon and the pressure causes precipitation to the diamond seed, growing a larger diamond. GIA compares the level of pressure from those presses to what you’d experience if you balanced a jumbo jet on the tip of your finger.

HPHT BARS press. By Heribero Arribas Abato

Optical tendencies

  1. Older HPHT operations are unable to eradicate brown. The presence of that undertone definitely remains present in the overall pipeline. There is one HPHT grower that been able to remove brown completely, but their output has a hint of blue.
  2. HPHT can have peculiar characteristics within. Since a metal catalyst is used some clarity characteristics present take on a decidedly metallic appearance. Here is a collection of photographs showing these unique characteristics.
  3. After superheating, the synthesized-diamond material can retract and pull away from an inclusion/fragment during the cooling process. This leaves a void with an identifiable inclusion that shows the diamond was absolutely man-made. It’s a clarity characteristic found nowhere in nature. The grading laboratories missed a chance to do something groundbreaking and create a new name for such man-made fragment/voids. Instead they call them crystals, in most cases.

HPHT rough material. Courtesy DIYTrade.

Value forecast

Synthetic-diamonds have been made since the 1950s. Technology has steadily improved and recently crossed a threshold where the cost to synthesize diamonds in factories dropped below the fixed expense needed to bring earth-mined diamonds to market.

Cost futures

As technology advances the principal of accelerating change suggests costs to produce synthetic-diamonds will continue to drop. In keeping with this theory, Element Six (a DeBeers subsidiary) recently launched Lightbox, offering laboratory-grown diamond jewelry for only $800 per carat. Some believe this DeBeers initiative will cause all synthetic-diamonds to lose value at an accelerated pace. 

Value futures

Natural diamond values historically rise with time. This creates a store of value for their owners, permitting natural diamond sellers to offer lifetime upgrade and even lifetime return, based on rising price points.

Alternately, as costs to produce them go down, synthetic-diamond values are forecast to drop. The product may be at its highest value the day it's purchased, becoming less and less valuable with time. While this may not bother shoppers making smaller purchases, the average engagement purchase still involves an outlay of thousands of dollars.

The FTC has been petitioned to require sellers of synthetic-diamonds to disclose this discrepancy to potential buyers.


Synthetic-diamonds are widely promoted as conflict-free and sustainable. And while they are certainly conflict-free, claiming them as "sustainable" is a double-edged sword. Sustainability is not exclusive to the environment. It also refers to economic development, inclusive participation and circular economy.


The natural diamond industry employs 10-million people in the poorest areas of the world. Each year it brings $8B into poor parts of Africa. So even if synthetic-diamonds are proven to be environmentally sustainable, is it ethical to guide shoppers' dollars away from developing countries where millions of people depend on natural diamond sales to make a living?

Energy consumption

The term “laboratory-grown” diamonds is actually a misnomer, since the facilities producing them are factories.

It's certain that sellers describing synthetic-diamonds as “Green” or “Eco-friendly” are in FTC violation. The Green Guides strictly prohibit environmental benefit claims which are difficult or impossible to substantiate. And, while the growers are not forthcoming with data, we know tremendous energy is consumed by diamond synthesis in both the HPHT and CVD processes.

A veteran grower has stated the most efficient HPHT multi-stone presses use between 350-750 kilowatt-hours per polished carat. Single-stone presses consume up to 1100 kWh per polished carat. CVD produces more unused rough so those energy requirements rise to 1,000-1,700 kWh per polished carat. And some HPHT growers using converted industrial presses require over 2,000 kWh per polished carat.

Using those estimates, the $1.9B of synthetic-diamonds sold in 2018 required enough production-energy to provide power to a sizeable population for the entire year. It may have been enough for Reno Nevada (250,000 people) or Atlanta GA (500,000 people) or somewhere in-between. We cannot be precise until the growers are willing to share their data, but the energy drain is inarguably tremendous. And as production increases so does that energy consumption footprint.

It’s worth noting that no conservation group has endorsed laboratory-grown diamonds, although many endorse electric cars.


There is nothing wrong with synthetic-diamonds. The purpose of this page is to help you become fully informed.

High Performance Diamonds does not offer laboratory-grown diamonds to our clients. This is primarily due to the absence of any future value, which goes against our core philosophies, lifetime guarantees and customer benefits.

With that said, if you have made the decision to buy a synthetic-diamond we know reputable sellers who offer them with full disclosure, and we will be happy to put you in-touch. Feel free to contact us for more information.

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