How lab-grown diamonds are made, graded, and sourced.
Manufacturing expertise, written plainly. What CVD and HPHT actually mean, what certification covers, and what drives price.
Advanced CVD & diamond growing technology
Chemical Vapour Deposition (CVD) grows diamonds in a controlled plasma chamber. We introduce hydrocarbon gas at precise temperatures. Carbon atoms deposit layer by layer onto a diamond seed. The result is a real diamond, atom by atom.
CVD gives us precise control over size, colour, and clarity. It produces Type IIA diamonds, the purest form of carbon crystal. Most premium colourless lab-grown diamonds in fine jewellery are CVD-grown.
From rough to graded: our quality control process
Every diamond grown at Mira Gems goes through a structured QC process before certification. Our technicians inspect each stone for inclusions, surface quality, and facet precision. Stones that don't meet grade thresholds are recycled rather than shipped.
- Internal grading against IGI standards
- Symmetry, polish, and cut grade verification
- Fluorescence and post-growth treatment documentation
- 100% certification before any stone leaves our facility
We document everything. You receive everything.
Trade buyers increasingly require full traceability documentation. Mira Gems provides production records, treatment disclosures, and certification reports with every order. Our documentation is designed for brands that operate under strict compliance and sourcing policies.
What certification means for lab-grown diamonds
IGI (International Gemological Institute) is the leading certifying body for lab-grown diamonds globally. Each IGI certificate documents the cut, colour, clarity, carat weight, fluorescence, and growth method. Every diamond from Mira Gems ships with an IGI report.
- Cut grade: Excellent to Good
- Colour: D (colourless) to Z (light yellow)
- Clarity: IF (internally flawless) to I2
- Carat weight: stated to two decimal places
- Growth method: CVD or HPHT, clearly noted
- Post-growth treatment: disclosed on certificate
CVD vs HPHT: what's the difference?
Both methods produce real, genuine diamonds. The difference is in the growing process.
CVD
Chemical Vapour Deposition
- Grows diamonds in a plasma chamber using carbon-rich gas
- Produces flat, tabular rough, ideal for rounds and fancy shapes
- Typically Type IIA, the highest purity
- May require post-growth treatment to remove brown tint
- Preferred for D–F colourless diamonds
HPHT
High Pressure, High Temperature
- Replicates the conditions deep inside the Earth
- Carbon dissolved in a metallic solvent under extreme pressure and heat
- Produces cubic or cuboctahedral rough, suited to larger stones
- Can grow naturally near-colourless or fancy-coloured diamonds
- Also used to treat off-colour CVD diamonds after growth
What is an HPHT diamond?
HPHT stands for 'high pressure, high temperature'. It is a method of growing diamonds by recreating the extreme pressure and heat conditions found deep underground. HPHT is also used as a post-growth treatment to enhance the colour of CVD diamonds.
What does the term 'HPHT diamond' mean?
An HPHT diamond is a diamond grown or treated using high-pressure and high-temperature technology. The term can refer to the growth method, or to a colour-enhancement treatment applied after CVD growth.
What is HPHT diamond treatment?
HPHT treatment is applied to CVD diamonds that have a residual brown or grey tint after growth. The stone is placed under extreme pressure and heat, which restructures the crystal lattice and produces a colourless or near-colourless result. All HPHT-treated diamonds at Mira Gems are disclosed on their IGI certification.
What is post-growth treatment in lab diamonds?
Post-growth treatment refers to any process applied to a lab-grown diamond after it has been grown to improve its optical properties. For CVD diamonds, the most common treatment is HPHT annealing, which removes residual tint and achieves colourless or near-colourless grades. All treatments are disclosed and certified.
Understanding the 4Cs of diamonds
The 4Cs are the global standard for grading diamond quality. Every stone from Mira Gems is assessed and certified against these criteria.
Cut
Determines brilliance and fire. Ranges from Excellent to Poor.
Colour
Measures the absence of colour. D is colourless, Z is light yellow.
Clarity
Measures internal and surface characteristics. IF is the highest; SI2 is visible under magnification.
Carat
The weight of the diamond. One carat equals 0.20 grams.
What is the price of a 1-carat lab-created diamond?
Lab-grown diamond prices depend on cut, colour, clarity, and certification. At wholesale, 1-carat lab-grown diamonds vary significantly based on grade. Contact our team for a volume-based quote.
What is the lab-grown diamond price, and what drives it?
Prices are determined by the 4Cs and the growing method (CVD or HPHT). They have become more competitive as manufacturing technology has improved.
How synthetic diamonds are generated
Lab-grown diamonds begin as a diamond seed, a thin slice of an existing diamond. In CVD, the seed is placed in a plasma chamber, carbon-rich gas is heated to a plasma state, and carbon atoms deposit on the seed to form a crystal over several days or weeks. In HPHT, the seed is embedded in carbon source material inside a press, where extreme pressure and temperature cause carbon to crystallise around it.
Both processes produce diamonds with the same physical, chemical, and optical properties as mined diamonds. The International Gemological Institute and other grading bodies grade lab-grown diamonds using identical standards to mined stones.
Why global buyers are choosing lab-grown diamonds
Lab-grown diamonds now account for a significant and growing share of the global diamond jewellery market. Consumers choose them for value, sustainability, and ethical assurance. Retailers choose them for margin, supply reliability, and consumer demand.
- Identical physical and optical properties to mined diamonds
- Available at a significant cost advantage
- No mining, and fully conflict-free
- Full certification and traceability
- Growing consumer demand across the USA, Europe, the Middle East and Asia
Dealer access. Live inventory. Direct pricing.
Registered wholesale buyers access our full inventory through the Mira Gems trade portal. Browse certified stock, submit orders, and track shipments in real time.