Lab-grown fancy color diamonds are created using two primary methods:
High-Pressure High-Temperature (HPHT) Method
In the HPHT process, a small diamond seed is placed in a carbon-rich environment under extreme heat (around 1,500°C) and pressure (up to 60,000 atmospheres). The carbon melts and crystallises around the seed, forming a diamond.
The diamond’s colour is influenced by specific trace elements introduced during growth:
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Nitrogen – Produces yellow or orange hues.
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Boron – Results in blue shades.
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Nickel – Can create green or grey tones.
Chemical Vapour Deposition (CVD) Method
In the CVD process, a diamond seed is placed in a chamber filled with carbon-rich gas, such as methane. The gas is heated using microwaves, causing carbon atoms to bond to the seed and form a diamond layer.
Colour is introduced through trace elements or post-growth treatments:
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Irradiation or annealing – Can create pink, purple, and green hues.
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Structural defects or lattice distortion – May result in unique colours and zoning patterns.
Both methods produce diamonds that are chemically identical to natural fancy colour diamonds, with controlled processes allowing for consistency and customisation in colour.