How lab-grown diamonds are made
A Swedish team made diamond in 1953 and stayed quiet until after General Electric went public in 1955.
- stations
- 6
- things upstream
- 5
- raw sources
- 3
- steps from the ground
- 3
The short version
Lab-grown diamonds are made two ways. In a giant press, carbon dissolves in molten metal around 1,500 °C and crystallizes on tiny diamond seeds. In a sealed chamber, energized methane and hydrogen form a plasma, and carbon settles on a thin seed plate layer by layer. Both take weeks or less, and the rough is then sawn, cut and polished like a mined stone.
-
Prepare the carbon source
Pressure growth packs high-purity carbon such as graphite beside a solvent metal such as nickel. Vapor growth feeds in a gas mix that is typically 1 part methane to 99 parts hydrogen.
-
Squeeze and heat
In the high-pressure route, a belt, cubic or split-sphere press clamps the cell between hard anvils, reaching about 5 GPa. Current through the anvils heats it above 1,400 °C and melts the metal.
5 GPa at about 1,500 °C
-
Crystallize on seeds
The molten metal dissolves the carbon and carries it to small seeds at the bottom of the press, where it precipitates as a growing crystal. A stone takes days to a few weeks.
-
Or deposit from plasma
In the vapor route, microwaves or another energy source ionize the gas above a substrate kept at about 800 °C. Carbon settles on a thin seed layer by layer, while hydrogen etches away any non-diamond carbon.
about 800 °C substrate
-
Assess the rough
The rough crystal comes out of the press or chamber and is assessed. Stones from a press can hold inclusions from the nickel, and chamber materials can contaminate plasma-grown ones.
-
Saw, cut and polish
From here the work matches that on mined stones: rough gets cleaved or sawn, cutters polish it on the same kinds of wheels, and it is later graded on the usual four measures.
Worth repeating
- Sweden's ASEA made the first known synthetic diamond on February 16, 1953, but its board chose not to publicize or patent it.
- Howard Tracy Hall at General Electric achieved the first commercially successful diamond synthesis on December 16, 1954.
- Lab-grown stones mostly stayed under half a carat until about 2010.
Back to the ground
Follow every input upstream and lab-grown diamond starts as these 3 raw sources.
Everything it is made of See it on the map
Open the whole family tree
Keep walking
Sources
Cite this page: "How lab-grown diamonds are made." Assembly Line, 2026-11-03. https://assemblyline.org/make/synthetic-diamond