As a GIA certified gemologist with over 20 years of experience, I’m often asked about lab-created diamonds. One method of producing synthetic diamonds that many are curious about is chemical vapor deposition, or CVD.
CVD diamonds, also known as lab-grown diamonds, are created through a process called chemical vapor deposition. These diamonds have the same physical and chemical properties as natural diamonds but are produced in a controlled laboratory environment. They offer an ethical and more affordable alternative to mined diamonds.
In this article, I’ll provide an in-depth look at what CVD diamonds are, how they’re made, their characteristics, and how they compare to natural diamonds and other lab-grown options. Whether you’re a jeweler sourcing stones or a consumer considering your options, understanding CVD diamonds can help you make informed purchasing decisions.
What are CVD Diamonds?
CVD diamonds are lab-created diamonds produced through a process called chemical vapor deposition. In chemical vapor deposition, diamonds are formed by depositing carbon atoms on a substrate within a high-tech vacuum chamber. Hydrocarbon gases like methane are introduced into the chamber and broken down into plasma using microwaves or hot filaments, releasing carbon atoms that settle onto the diamond seed plate.
The carbon atoms accumulate in an organized crystalline structure, replicating how diamonds form underground naturally. Advanced CVD systems use tailored conditions of low pressure, high heat up to 1600°C, and gas composition to optimize the diamond growth process. The resulting CVD diamonds exhibit the same exceptional hardness, brilliance, and fire as natural diamond.
Compared to other lab diamond production methods like HPHT, CVD offers greater control over crystal formation, allowing for diamonds with excellent cut, clarity, and color. CVD is currently the most advanced and popular technique for producing synthetic diamonds.
How are CVD Diamonds Made?
The CVD diamond production process utilizes complex, highly engineered equipment. Here are the key stages involved:
1. Vacuum Chamber Preparation
The process takes place within a vacuum chamber, with conditions optimized for diamond formation. The chamber is sealed and pumped to low pressure levels to remove impurities.
2. Hydrocarbon Gas Introduction
Gases like methane or ethane are piped into the chamber. The gases act as a source of carbon for building the diamond crystal.
3. Gas Breakdown
Energy is applied in the form of microwaves or heated filaments, breaking the gas molecules down into plasma. This releases carbon atoms needed for diamond crystallization.
4. Deposition on Diamond Seeds
A thin diamond substrate or “seed” plate is introduced. The liberated carbon atoms deposit on the plate, forming the diamond crystal structure.
5. Controlled Diamond Growth
By carefully managing the environment within the chamber, the diamond lattice grows outward from the seed. Growth rates can be over 300x faster than natural diamonds.
6. Harvesting Grown Diamonds
Once complete, the grown diamonds are removed from the chamber. Larger diamonds may be cut into smaller stones.
Are CVD Diamonds Good Quality?
With innovations in CVD technology, the quality of synthetic diamonds now rivals that of mined diamonds. Since they have the same chemical structure and composition, CVD diamonds have exceptional hardness, brilliance, and dispersion.
Cut quality for CVD diamonds has vastly improved, with advanced laser and automated cutting allowing for ideal proportions and symmetry. CVD diamonds can achieve colorless grades as high as D-E-F, with absence of impurities resulting in exceptional clarity as well.
While exceptions exist, the highest quality CVD diamonds match or exceed the 4Cs of most natural counterparts. Concerns around inferior quality synthetic diamonds are outdated – “lab-grown” no longer equates to “lower grade” with modern manufacturing capabilities.
Pros and Cons of CVD Diamonds
CVD diamonds offer several advantages over natural diamonds:
- Cost savings – CVD diamonds retail for 30-50% less than comparable mined diamonds. Savings allow more people to afford large, high quality stones.
- Ethical sourcing – The mining industry has faced criticism around working conditions and environmental impact. CVD sidesteps these concerns.
- Predictable characteristics – Growth in controlled conditions results in consistent color, clarity, and cut.
- Sustainability – CVD production has less waste and energy usage than mining.
- Conflict-free – CVD diamonds do not originate from conflict zones linked to the diamond trade.
However, CVD diamonds also have some drawbacks to consider:
- No resale value – Like other synthetics, CVD diamonds do not hold resale value compared to natural diamonds.
- Not as sentimental – For events like engagements, some prefer “real” diamonds with emotional value.
- Detection challenges – Advanced tools are needed to identify lab-grown diamonds and avoid fraud.
- Limited production size – The largest CVD-grown diamond is a 34.59-carat diamond from a lab in India.
For buyers open to lab-created diamonds, the advantages often make CVD an appealing option. But resale concerns may deter those wanting natural investment diamonds.
CVD Diamond Price and Value Comparison
Due to lower production costs, CVD diamonds sell for 30-50% less than equivalent natural diamonds. For a 1 carat, high quality CVD diamond, price averages around $3,000 compared to $6,000 for an ideal cut, D color, VVS2 clarity mined diamond.
Price differences depend on the 4Cs. An excellent cut CVD with E color may sell for 80% of a like-quality natural diamond. For lower colors like K-M, CVD savings grow to 50-60%. Clarity has less impact on price difference.
Compared to other lab diamonds, CVD also carries a 10-30% discount against HPHT. However, with no used retail market, all lab diamonds suffer from depreciation. Natural diamonds typically retain 50-100% of initial value based on cut, color and clarity grades.
Price Comparison Table (Estimated): CVD vs. Natural Diamonds
|Diamond Type||Carat||Color||Clarity||Estimated Price (Average)|
|CVD Diamond||1 carat||D-E-F||VVS2||$3,000 – $5,000|
|Natural Diamond||1 carat||D||VVS2||$6,000 – $8,000|
|CVD Diamond||1 carat||E||VS1||$2,500 – $4,000|
|Natural Diamond||1 carat||F||VS1||$4,000 – $6,000|
|CVD Diamond||1 carat||G-H||SI1||$1,500 – $2,500|
|Natural Diamond||1 carat||G-H||SI1||$2,000 – $3,500|
Overall, CVD presents significant price savings for large, high quality diamonds. But those wanting resale value are still better served by a natural, graded diamond purchased from a reputable supplier.
How to Tell if a Diamond is CVD
Identifying lab-created diamonds like CVD requires advanced testing methods. Gemologists use tools like:
- GIA or IGI Lab Reports – Will state if diamond is CVD or natural.
- PCR Test – Detects trace impurities from lab growth.
- Spectrometer – Measures optical properties that differ in CVD diamonds.
- Loupe Inspection – Trained eyes may spot striations, extra facets, or crystal flaws.
- Laser Inscription – Lab diamonds have a permanent laser marking, usually on girdle.
Consumers should beware of diamond fraud – make sure any diamond has been certified, and shop with reputable jewelers. Indicators that may aid identification of CVD:
- Very large carat sizes for low prices
- Unnaturally perfect color/clarity combinations
- Slight fluorescence, phosphorescence
- Minor spectrometer variations compared to natural diamond
Purchase diamonds with proper lab reports. For settings mixing natural and CVD, make sure each is disclosed as such.
CVD vs. Natural vs. Other Lab-Grown Diamonds
|Characteristic||CVD Diamonds||Natural Diamonds||Other Lab-Grown Diamonds|
|Price Range||30-50% less||Varies||Varies|
|Color and Clarity||Up to D-E-F||Varies||Varies|
|Identification Methods||Advanced tools||Visual inspection||Advanced tools|
Frequently Asked Questions
Do CVD diamonds last as long as real diamonds?
Yes, CVD diamonds have the same exceptional hardness and durability as natural diamond. They maintain the same brilliance and fire when cared for properly.
What are CVD diamonds best used for?
CVD diamonds work well for jewelry, especially bridal designs needing large center stones. Their controlled growth also makes them ideal for industrial applications.
How fast can CVD systems produce diamonds?
CVD reactors can grow crystals at rates over 300x faster than natural diamonds form underground – up to 2 carats per month for high quality diamonds.
What is the largest CVD diamond created?
Most CVD reactors are optimized for smaller diamonds under 1 carat. But advances have enabled creation of single diamonds up to 34 carats as of 2023. Progress continues toward even larger CVD stones.
Can CVD pass a diamond tester?
Yes, CVD diamonds have the same chemical composition and crystal structure as natural diamonds, so they share many of the same physical properties, including thermal conductivity. However, advanced testing methods have been developed to distinguish between CVD diamonds and natural diamonds with greater accuracy.
Some methods that can be used to identify CVD diamonds are Advanced Diamond Testers with more sophisticated algorithms and multiple test parameters, Raman spectroscopy and photoluminescence spectroscopy. The technology used in diamond testing is continually evolving, and as lab-grown diamonds become more prevalent in the market, testing methods are improving to accurately identify them.
CVD diamonds are a type of lab-grown diamond that offer excellent quality. They have similar physical and chemical properties to natural diamonds, but are created in a controlled environment.
While they may be more affordable than natural diamonds, their quality can vary depending on the manufacturer and production process. Consumers have more options than ever for ethically sourced, expertly cut synthetic diamonds.
While the secondhand value and emotional appeal of natural diamonds persists for some buyers, CVD presents an innovative, sustainable alternative.
I hope this guide has provided clarity on what CVD diamonds are, how they’re produced, and how they compare to other diamond origins. Let me know if you have any other questions!