Overview

A lab-grown diamond is a diamond manufactured in a controlled laboratory environment rather than formed by geological processes deep within the Earth. The distinction is purely one of origin. The crystal structure is the same — carbon atoms bonded in a face-centred cubic lattice through sp3 hybridisation. The physical properties are the same: Mohs 10 hardness, 2.417 refractive index, 0.044 dispersion. The optical behaviour is the same. To the naked eye, to a loupe, and to every standard gemological test, a lab-grown diamond is indistinguishable from a natural one.

Two production methods account for virtually all gem-quality lab-grown diamonds on the market today. High Pressure, High Temperature (HPHT) synthesis recreates the conditions of the Earth's mantle — extreme pressure and temperature that force carbon to crystallise on a diamond seed. Chemical Vapour Deposition (CVD) takes a fundamentally different approach, growing diamond layer by layer from a carbon-containing gas in a low-pressure plasma chamber. Each method produces stones with distinct internal characteristics that trained gemologists and specialised instruments can identify.

The lab-grown diamond market has expanded rapidly since approximately 2015. Manufacturing volumes have increased, production costs have fallen, and prices to consumers have declined significantly — roughly 70 % between 2022 and 2024. The GIA and other major laboratories now issue dedicated grading reports for lab-grown diamonds, applying the same 4Cs framework used for natural stones.

Key Concepts

Two methods, two sets of characteristics. HPHT diamonds grow under 5–6 GPa of pressure at 1,300–1,600 °C, forming cuboctahedral crystals that may contain metallic flux inclusions. CVD diamonds grow at much lower pressure in a plasma chamber, forming tabular crystals that are often inclusion-free but may show growth striations. Understanding which method produced a stone helps explain its internal features and how it was identified. See How HPHT Diamonds Are Grown and How CVD Diamonds Are Grown.

Post-growth treatment is standard practice. Approximately 80 % of CVD diamonds submitted to the GIA since 2020 have undergone post-growth HPHT treatment to remove brown colour caused by vacancy defects during rapid growth. This is disclosed on the grading report. See Post-Growth Processing.

Terminology has evolved. The GIA retired the term "synthetic" in 2019 because it misled consumers into thinking lab-grown diamonds were not real diamonds. The approved terms are "laboratory-grown" and "laboratory-created." See Lab-Grown Terminology.

Grading follows the same 4Cs. Since 2020, the GIA Laboratory-Grown Diamond Report includes full colour, clarity, cut, and carat weight grades — the same framework applied to natural diamonds. The report format is visually distinct and notes the growth method.

Practical Tips

Know what you are buying. A lab-grown diamond is a genuine diamond. It is not cubic zirconia, moissanite, or any other simulant. If a seller uses vague language, ask to see the grading report.
Check the grading report format. GIA reports for lab-grown diamonds are clearly labelled and include the growth method (CVD or HPHT). The stone's girdle is inscribed with "Laboratory-Grown."
Understand the price trajectory. Lab-grown diamond prices have declined sharply and are expected to continue falling as production scales. This is relevant if resale value matters to your purchase decision.
Compare within the same category. Lab-grown diamonds should be compared to other lab-grown diamonds on the 4Cs, not benchmarked against natural diamond pricing. The markets operate on different fundamentals.

What the Child Articles Cover

Lab-Grown Terminology — approved and retired terms, FTC guidance, and why language matters in this market.
How HPHT Diamonds Are Grown — the high-pressure process, apparatus types, growth conditions, and characteristic inclusions.
How CVD Diamonds Are Grown — the plasma deposition process, growth rate, crystal shape, and typical features.
Post-Growth Processing — HPHT treatment of CVD stones, colour modification, cutting, polishing, and laser inscription.

Lab-Grown Overview

Terminology: "Laboratory-Grown" vs "Synthetic"

How HPHT Diamonds Are Grown

How CVD Diamonds Are Grown

Post-Growth Processing