CVD vs HPHT Diamonds: What's the Difference?
CVD vs HPHT Diamonds: What's the Difference?
Two methods, one result: a real diamond
All lab-grown diamonds are made using one of two scientifically established processes: Chemical Vapour Deposition (CVD) or High Pressure High Temperature (HPHT). Both produce real diamonds with the same chemical composition, physical hardness, and optical properties as mined diamonds. Both can be graded and certified by IGI. The method of growth does not affect the diamond's appearance, durability, or value in a meaningful way for the end buyer.
How CVD works
CVD stands for Chemical Vapour Deposition. A thin slice of an existing diamond (the seed crystal) is placed inside a sealed low-pressure chamber. A carbon-rich gas, usually methane, is pumped in and broken down using microwave energy or laser technology. The ionised carbon atoms are attracted to the seed crystal and deposit onto it one atomic layer at a time, gradually building a full diamond crystal. The process takes approximately six to eight weeks per stone. CVD produces diamonds that are typically high in colour (D to F range) and are the more commonly used method for gem-quality lab-grown stones today.
How HPHT works
HPHT stands for High Pressure High Temperature. This method replicates the conditions found approximately 100 miles below the earth's surface where natural diamonds form. A diamond seed is placed in a growth cell along with a carbon source. The cell is compressed to pressures exceeding 1.5 million PSI and heated to temperatures above 2,000 degrees Fahrenheit (approximately 1,300 to 1,600 degrees Celsius). Under these conditions, the carbon melts and crystallises around the seed, forming a diamond over days to weeks. HPHT was the first method used to grow diamonds in a laboratory (developed in the 1950s) and is often used to produce large, high-clarity stones.
CVD vs HPHT: comparison
| Property | CVD | HPHT |
|---|---|---|
| Growth method | Carbon gas deposited layer by layer onto a seed crystal | Carbon melted and crystallised under extreme pressure and heat |
| Pressure | Low pressure (vacuum chamber) | Very high (1.5 million+ PSI) |
| Temperature | 700-1,000°C | 1,300-1,600°C |
| Growth time | 6-8 weeks | Days to several weeks (varies by size) |
| Crystal shape | Cubic (flat plates, stacked) | Cuboctahedron or cube form |
| Colour range | D-J. Frequently D-F (colourless range) | D-J. Strong in the colourless and near-colourless range |
| Typical use | Gem-quality jewellery; most common in consumer market | Gem-quality jewellery; industrial applications |
| IGI grading | Yes. Growth method noted on certificate. | Yes. Growth method noted on certificate. |
| Identifiable by eye? | No | No |
Are both CVD and HPHT diamonds real diamonds?
Yes. Both CVD and HPHT diamonds are real diamonds. Their carbon atom arrangement is the diamond cubic crystal structure, identical to mined diamonds. They register as diamonds on every standard diamond testing instrument. They can be cut, polished, and set using the same techniques as mined diamonds. The terms CVD and HPHT describe the production method only, not the final material.
Which is better: CVD or HPHT?
Neither method is inherently superior. Both produce gem-quality diamonds across the full colour and clarity range. CVD is more commonly used for consumer gem-quality diamonds today because the process is highly controllable and tends to produce very high colour grades at scale. HPHT is effective for producing large stones and is also used to treat mined diamonds to improve colour. For a buyer, the growth method has no practical impact on the diamond's appearance, durability, or wearability.
Nivara uses both CVD and HPHT diamonds in its collection, selecting individual stones based on their IGI-certified grade rather than growth method. The IGI certificate for every Nivara diamond states the growth method explicitly.
How to identify which method was used
The IGI certificate for every lab-grown diamond states the growth origin (e.g., "Laboratory-Grown: CVD" or "Laboratory-Grown: HPHT"). The laser inscription on the diamond's girdle includes the certificate number, which links to the full grading report. This information is always available for any Nivara diamond.
Frequently asked questions
Can you tell CVD from HPHT with the naked eye?
No. CVD and HPHT diamonds look identical visually. Even trained gemologists using standard microscopes cannot distinguish between them by appearance. The IGI certificate is the definitive source for growth method.
Does the growth method affect the diamond's resale value?
In practice, no. Resale value for lab-grown diamonds of both types is determined by the same factors as any diamond: colour, clarity, cut, and carat weight as stated on the IGI certificate. There is no established premium or discount for either growth method in the current market.
Are there quality differences between CVD and HPHT diamonds?
Not inherently. Both methods can produce diamonds across the full quality spectrum, from lower grades to D Flawless. The specific grade of each stone (as certified by IGI) is what determines quality, not the method used to produce it.
Does Nivara sell both CVD and HPHT diamonds?
Yes. Nivara selects diamonds based on IGI-certified grade and appearance rather than growth method. All Nivara diamonds carry individual IGI certificates that specify the growth method.
Is HPHT treatment the same as HPHT grown diamonds?
No. HPHT treatment is a post-growth process applied to some mined or lab-grown diamonds to improve their colour. HPHT-grown diamonds are diamonds produced from scratch using the HPHT growth method. These are distinct processes. IGI certifications distinguish between the two.
Lab-grown vs natural diamonds: the full comparison | Learn more about lab-grown diamonds
