When researching lab-grown diamonds, two terms come up repeatedly: CVD and HPHT. These are the two primary methods used to grow lab-grown diamonds, and understanding the difference helps you make a more informed purchase. This guide explains both methods clearly, compares their characteristics, and tells you which Inasha Diamonds uses and why.
What Is CVD?
CVD stands for Chemical Vapour Deposition. In this process, a thin diamond seed crystal (a slice of existing diamond) is placed in a sealed chamber. The chamber is filled with carbon-rich gases - typically methane mixed with hydrogen. Microwave energy or a laser ionises the gas mixture into plasma, causing carbon atoms to separate from the gas and deposit layer by layer onto the seed crystal, growing a real diamond crystal upward over several weeks.
The result is a diamond with a columnar growth structure - layers building upward like a stack. CVD diamonds are typically grown as rough rectangular crystals, then cut and polished using the same techniques as natural diamonds.
What Is HPHT?
HPHT stands for High Pressure High Temperature. This method replicates the geological conditions under which natural diamonds form deep in the earth. A small diamond seed is placed in a growth cell containing carbon source material (typically graphite or diamond powder). The cell is subjected to extreme pressure (approximately 1.5 million pounds per square inch) and extreme temperature (around 1,500 degrees Celsius) using a belt press, cubic press, or split-sphere press. Carbon dissolves from the source material and deposits onto the seed crystal, growing a diamond over several days to weeks.
HPHT diamonds often grow in a cuboctahedral shape - a combined cube and octahedron - reflecting the cubic crystal structure of diamond. They are then cut and polished like natural diamonds and CVD diamonds.
CVD vs HPHT - Quality Comparison
Both methods produce real diamonds with identical chemical composition, hardness, and optical properties to natural diamonds. Neither method produces a superior diamond inherently - quality is determined by the specific growth conditions, the skill of the grower, and the subsequent cutting and polishing, not by the growth method itself.
Colour: CVD diamonds can sometimes exhibit a brownish or greyish tint during growth due to the presence of nitrogen or other trace elements in the growth chamber. This can be corrected through post-growth HPHT treatment. Well-controlled CVD processes produce D-F colourless diamonds without treatment. HPHT diamonds can exhibit a yellowish tint if nitrogen is not carefully excluded from the growth cell. Both methods can produce colourless D-F diamonds when processes are properly controlled.
Clarity: Both methods can produce VVS and higher clarity diamonds. CVD diamonds may show characteristic needle-like inclusions along the growth direction. HPHT diamonds may show metallic flux inclusions from the growth media. Neither type of inclusion affects the diamond's beauty in VS clarity and above grades.
Size: HPHT produces diamonds in larger rough sizes more readily than early CVD technology. However modern CVD technology in 2026 can produce large rough crystals suitable for 3 carat+ finished diamonds, making this difference increasingly irrelevant.
Which Is Better - CVD or HPHT?
Neither is definitively better. Both methods produce IGI-certified lab-grown diamonds of identical quality when grown and cut to the same specifications. The finished, polished, IGI-certified diamond is what matters - not the growth method. An IGI-certified D/VVS1/Excellent cut CVD diamond and an IGI-certified D/VVS1/Excellent cut HPHT diamond of the same carat weight are effectively equivalent in quality and value.
The distinction that matters is the IGI certificate - which confirms the exact 4Cs regardless of growth method - and the cut quality, which determines brilliance and fire. Always evaluate a lab-grown diamond by its IGI-certified 4Cs, not by its growth method.
Does the IGI Certificate Specify CVD or HPHT?
Yes. IGI certificates for lab-grown diamonds include the growth method - the certificate will state either CVD or HPHT under the origin description. This is transparent and standard. Both growth methods are fully disclosed and certified by IGI using identical grading standards for Cut, Colour, Clarity, and Carat weight.
Which Method Does Inasha Diamonds Use?
All lab-grown diamonds sold by Inasha Diamonds are CVD grown. We use CVD exclusively because modern CVD technology produces consistently excellent colour and clarity in the grades we offer, with the full transparency of IGI certification specifying the growth method on every certificate.
CVD is currently the dominant growth technology for gem-quality lab-grown diamonds globally - the majority of IGI-certified lab-grown diamonds sold by reputable brands worldwide are CVD grown. HPHT continues to be used and produces excellent quality stones, but CVD has become the industry standard for colourless, gem-quality diamond production at scale.
Can You Tell CVD from HPHT by Looking at the Diamond?
No. You cannot distinguish a CVD from an HPHT diamond by visual inspection, standard diamond tester, or jewellery loupe. Both look identical when cut and polished to the same specifications. Only specialised spectroscopic equipment at gemological laboratories can identify the growth method - and the IGI certificate will disclose this clearly.
Does Growth Method Affect Price?
Not significantly at the retail level. Both CVD and HPHT diamonds of identical IGI-certified 4Cs are priced comparably. If anything, HPHT diamonds may carry a slight premium in some markets due to their longer production history, but this difference is minor and not universal. The 4Cs and IGI grade drive price far more than the growth method.
Summary - CVD vs HPHT
CVD uses gas deposition at moderate temperatures and pressures. HPHT uses extreme pressure and temperature replicating geological conditions. Both produce real diamonds identical to natural diamonds. Both are IGI-certified using the same 4Cs standards. Both growth methods are disclosed on the IGI certificate. Quality is determined by 4Cs and cut, not growth method. Inasha Diamonds uses CVD exclusively. For any diamond purchase, evaluate by IGI-certified 4Cs - not by growth method.
Shop IGI-Certified CVD Lab-Grown Diamond Jewellery at Inasha Diamonds
Every Inasha Diamonds diamond is IGI-certified CVD lab-grown, with the growth method stated on the certificate. Report numbers are laser-inscribed on every diamond's girdle and verifiable at report.igi.org. Rings from Rs. 34,000. Earrings from Rs. 11,000. All set in BIS Hallmark gold or 950 platinum. Free insured shipping across India. Email: help@inashadiamonds.com | WhatsApp: +91 6003557006 | Website: inashadiamonds.com