Two Methods, One Result: Real Diamonds
Lab-grown diamonds are created using two distinct technologies, each replicating the natural conditions under which diamonds form — just in weeks instead of billions of years. Both methods produce genuine diamonds that are physically, chemically, and optically identical to mined diamonds. Here is how each process works.
HPHT: High Pressure High Temperature
- The concept: HPHT mimics the conditions deep within the Earth where natural diamonds form — extreme pressure and extreme temperature applied to carbon
- The process: A small diamond seed (a tiny sliver of existing diamond) is placed in a chamber with a carbon source (typically graphite). The chamber is subjected to approximately 1,500°C (2,700°F) and 1.5 million pounds per square inch of pressure
- What happens: Under these extreme conditions, the carbon source melts and begins to crystallize around the diamond seed, atom by atom, building a larger diamond crystal over days to weeks
- Result: A rough diamond crystal that can be cut and polished using the same techniques as mined diamonds
- Characteristics: HPHT diamonds often have a slightly different growth pattern than natural diamonds (cuboctahedral vs octahedral), which gemological labs can detect with specialized equipment. Visually, they are indistinguishable
CVD: Chemical Vapor Deposition
- The concept: CVD grows diamonds from a carbon-rich gas plasma in a vacuum chamber — essentially raining carbon atoms onto a diamond seed
- The process: A thin diamond seed is placed in a sealed vacuum chamber. The chamber is filled with a carbon-containing gas (typically methane). The gas is heated to 800-900°C using microwaves, creating a plasma
- What happens: The extreme heat breaks the molecular bonds of the gas, releasing individual carbon atoms. These atoms drift downward and deposit onto the diamond seed, building the crystal layer by layer
- Result: A flat, tabular diamond crystal that grows upward from the seed plate. This crystal is then cut and polished like any other diamond
- Characteristics: CVD diamonds tend to have different strain patterns than HPHT or natural diamonds. Again, only detectable with laboratory equipment — not by any human observation
HPHT vs CVD: Does It Matter to the Buyer
- Short answer: No. Both produce real diamonds with identical physical and optical properties. The creation method does not affect the diamond's beauty, hardness, or durability
- Quality: Both methods can produce diamonds across the full quality spectrum — from low-grade industrial diamonds to flawless, colorless gems. Quality depends on the manufacturer's expertise, not the method
- Grading: Both HPHT and CVD diamonds are graded by IGI and GIA using the same 4C criteria. An Excellent cut, F color, VS2 clarity diamond is the same quality regardless of whether it was grown by HPHT or CVD
- Price: Generally comparable for similar quality. Neither method produces significantly cheaper diamonds than the other at retail
How Labs Detect Growth Method
- Photoluminescence spectroscopy reveals different defect patterns
- Growth morphology analysis shows cuboctahedral (HPHT) vs layered (CVD) growth patterns
- UV fluorescence patterns differ between the two methods
- All of these require specialized laboratory equipment — no human can detect the difference visually