Humans can manufacture diamonds in a laboratory setting, resulting in a material chemically and structurally identical to those formed deep within the Earth. These are known as laboratory-grown diamonds (LGDs). An LGD is pure carbon crystallized in the characteristic cubic lattice structure, possessing the same optical, physical, and chemical properties as its mined counterpart. This advancement relies on replicating the extreme conditions necessary for carbon atoms to bond into the diamond structure, allowing for the creation of gem-quality diamonds for jewelry and industrial applications.
The Core Methods of Creation
Scientists employ two primary methods to synthesize diamonds: High-Pressure/High-Temperature (HPHT) and Chemical Vapor Deposition (CVD). The HPHT method mimics the conditions under which natural diamonds form within the Earth’s mantle. This process involves placing a small diamond seed crystal, a carbon source (like graphite), and a metal solvent/catalyst (often an alloy of iron, nickel, or cobalt) into a massive press.
The press subjects this internal cell to immense pressure, typically 5 to 6 Gigapascals (GPa). Simultaneously, the temperature is raised between 1,300 and 1,600 degrees Celsius. The molten metal catalyst dissolves the carbon source, allowing carbon atoms to precipitate and crystallize onto the cooler diamond seed. This process grows the crystal over a period of several weeks.
The second technique, Chemical Vapor Deposition (CVD), relies on a vacuum chamber and carbon-rich gases. A diamond seed is placed inside the chamber, which is then filled with a gas mixture, such as methane and hydrogen, at a much lower pressure than HPHT. Energy, often a microwave beam, breaks down the gas molecules, creating a plasma cloud.
Carbon atoms are liberated from the gas and slowly deposit, layer by layer, onto the seed crystal. The temperature during the CVD process is maintained between 700 and 1,200 degrees Celsius. This technique results in a square-shaped, plate-like rough diamond and is valued for producing diamonds with very low nitrogen content, known as Type IIa diamonds.
Scientific Identity of Lab Grown Diamonds
The scientific identity of a laboratory-grown diamond is defined by its atomic structure and composition, identical to a natural diamond. Both LGDs and natural diamonds are composed of carbon atoms arranged in a stable, three-dimensional cubic lattice. This crystal arrangement is responsible for the unique properties of diamond, regardless of its origin.
This shared structure means LGDs exhibit the same physical properties as natural diamonds, including the highest rating of 10 on the Mohs scale of hardness. They share the same density and refractive index, which determines how light passes through the stone, creating brilliance and fire.
LGDs are fundamentally different from diamond simulants, such as cubic zirconia or moissanite. Simulants only look similar to a diamond but are made from different materials with distinct chemical formulas. For example, moissanite is silicon carbide, while an LGD is pure crystalline carbon.
Distinguishing Lab Grown from Natural Diamonds
While the chemical makeup of lab-grown and natural diamonds is identical, experts can distinguish them by analyzing subtle differences related to their formation environment. To the unaided eye, the two are indistinguishable, but gemological laboratories use advanced spectroscopy equipment to determine origin.
HPHT diamonds often contain microscopic metallic inclusions from the solvent/catalyst used during their growth, which serves as a key marker. Natural diamonds, conversely, typically feature mineral inclusions trapped during their geological formation deep underground. Furthermore, the two growth methods result in unique patterns within the crystal structure.
Natural diamonds typically grow in an octahedral pattern, while HPHT diamonds show a more geometric, blocky structure, and CVD diamonds exhibit a layered growth pattern. These patterns are made visible under specialized high-magnification scopes and polarized light. Additionally, the way each stone fluoresces under short-wave ultraviolet light can differ; for example, some HPHT diamonds may show a yellow or orange glow.
The most fundamental difference is the origin and time scale, with natural diamonds taking billions of years to form versus the few weeks required for lab creation. This difference in production time significantly impacts cost, making LGDs more affordable, often 30 to 50 percent less than a comparable mined diamond. The cost consistency and controlled purity also make LGDs valuable for industrial applications, such as high-performance cutting tools and advanced optics.