Industry analysts predict that by 2025, 20% of all diamonds in the market will be laboratory-grown. The gem industry has witnessed a remarkable rise in the quantity, size, and quality of lab-grown diamonds over recent years. Currently, GRSI processes more CVD-grown diamond submissions daily than it once did in an entire year, highlighting the growing demand. As a result, understanding the production, treatment, and identification of these diamonds is more crucial than ever.
This article explores key trends observed by GRSI since 2007, the year it began issuing grading reports for laboratory-grown diamonds.
Laboratory Growth and Treatment Methods
Most lab-grown diamonds analyzed at GRSI Laboratories are produced using the CVD (Chemical Vapor Deposition) method, with many undergoing post-growth HPHT (High-Pressure, High-Temperature) treatment to enhance their color.
CVD Diamonds
When CVD diamonds were first produced in 1952, their crystal quality and size were unsuitable for jewelry. However, by the 2000s, some gem-quality CVD diamonds emerged. In recent years, technological advancements have led to the mass production of high-quality CVD-grown diamonds.
CVD diamond growth follows a process distinct from natural diamond formation. This method involves a reactor where hydrogen and hydrocarbon gases (typically methane) flow over diamond substrates. Microwaves activate plasma, triggering a chemical reaction that deposits diamond material on the seeds. The high hydrogen content (90–99%) suppresses the formation of graphite or non-diamond carbon, ensuring high-quality growth.
HPHT Diamonds
Though the CVD method was developed earlier, the first gem-quality laboratory-grown diamonds were produced using the HPHT method. This technique mimics natural diamond formation by subjecting graphite to extreme pressures (5–6 GPa) and high temperatures (1300–1600°C), exceeding those found in Earth’s mantle.
The HPHT process takes place inside a capsule containing:
- A carbon source (typically graphite powder)
- A metallic flux to dissolve carbon and promote growth
- A diamond seed to initiate crystallization
Depending on the desired size and quality, HPHT diamonds can grow within hours to a few weeks.
For both methods, the quality and size of the diamond substrate play a crucial role in determining the final crystal’s characteristics.
Color, Clarity, and Carat Weight
Color
CVD-Grown Diamonds
Before 2020, most CVD-grown diamonds were near-colorless, with grades ranging from G to N. Many also exhibited a grayish hue. By 2020, advancements in growth and treatment methods significantly increased the production of colorless diamonds (D, E, or F).
Since CVD diamonds can develop brown coloration during growth, many undergo HPHT or LPHT (Low-Pressure, High-Temperature) treatment to remove brown tones and improve their color. This post-growth treatment has become a standard industry practice—since 2020, about 80% of CVD-grown diamonds analyzed by GRSI have undergone post-growth processing.
HPHT-Grown Diamonds
Early HPHT-grown diamonds were often yellow-orange (due to nitrogen impurities) or blue (due to boron). However, manufacturers have since refined the process to remove nitrogen, significantly reducing the presence of yellow-orange HPHT-grown diamonds. Today, over 90% of HPHT-grown diamonds are colorless, reflecting consumer preferences.
Clarity
Producing large, colorless HPHT-grown diamonds with high purity is challenging, as it requires carefully controlled conditions to minimize nitrogen content while ensuring optimal crystal growth. While CVD diamonds can grow in multiple stages, HPHT diamonds are produced in a single uninterrupted run, making precise control essential.
Carat Weight
The size of CVD-grown diamonds has increased dramatically over time. From 2000 to 2010, most submitted CVD diamonds were under 0.5 ct, but today, the majority exceed 3 ct. This growth reflects improvements in CVD technology and the availability of larger diamond substrates.
By January 2022, the largest faceted CVD-grown diamond was 16.41 ct. Since then, the record has quadrupled to 75.33 ct.
For HPHT-grown diamonds, some surpass 100 carats. The largest known HPHT-grown diamond, created in November 2021, weighed 150.42 ct.
Global Laboratory-Grown Diamond Production
An industry report estimated that 6–7 million carats of gem-quality lab-grown diamonds were produced worldwide in 2020. The top producers include:
- China – 3 million carats (mostly HPHT)
- India – 1.5 million carats (mostly CVD)
- United States – 1 million carats (mostly CVD)
Key Global Producers
- China – Specializes in mass-producing HPHT melee diamonds, as well as high-quality CVD-grown pink and blue diamonds.
- India – Home to 4,000–6,000 CVD reactors in Surat, India’s diamond hub. Indian manufacturers produced the largest known faceted CVD diamond (75.33 ct) in 2024.
- United States – Initially developed CVD diamonds for the semiconductor industry due to their superior thermal and optical properties.
Did You Know?
Most colorless to near-colorless laboratory-grown diamonds are Type II, meaning they lack nitrogen impurities. In contrast, only 1% of natural diamonds fall into this category.
Conclusion
The market for laboratory-grown diamonds is rapidly evolving, with improvements in growth techniques, color treatment, and carat sizes. As demand increases, so does the need for reliable identification and certification.
At GRSI Laboratories, we remain at the forefront of diamond analysis, ensuring transparency and accuracy in every evaluation.
Want to learn more about identifying laboratory-grown diamonds, including melee sizes? Read our full report today!