Lab-grown diamonds have emerged as a significant topic in the jewelry world. Many wonder if these diamonds, created in controlled environments, possess the same qualities as their natural counterparts. Understanding their formation, composition, and distinctions from other diamond-like materials is crucial for informed consumers.
Understanding Lab-Grown Diamonds
A lab-grown diamond is a genuine diamond, composed of pure carbon atoms arranged in a crystalline lattice structure, identical to natural diamonds. These diamonds are cultivated in a laboratory setting, replicating the geological processes that form natural diamonds deep within the Earth. This controlled creation process results in a material that is chemically, physically, and optically identical to a mined diamond.
Two primary methods are used to create lab-grown diamonds: High-Pressure/High-Temperature (HPHT) and Chemical Vapor Deposition (CVD). The HPHT method mimics the extreme heat and pressure conditions found in the Earth. It places a small diamond seed and carbon material into a chamber subjected to intense temperatures (over 2000 degrees Celsius) and pressures (around 1.5 million pounds per square inch). This process encourages carbon atoms to crystallize around the seed, forming a new diamond over several weeks.
The CVD method involves placing a diamond seed in a vacuum chamber filled with carbon-rich gases, such as methane and hydrogen. The chamber is heated to temperatures typically ranging from 700 to 1200°C, and microwaves are used to ionize the gases, creating a plasma cloud. Carbon atoms from this plasma then deposit layer by layer onto the diamond seed, growing a rough diamond over a period of weeks.
Lab-Grown and Natural Diamond Differences
Lab-grown diamonds are chemically, physically, and optically identical to natural diamonds, sharing the same pure carbon composition and crystalline structure. Both types score a 10 on the Mohs hardness scale, indicating exceptional durability and strength. They also exhibit the same brilliance and fire. The fundamental difference lies solely in their origin: one forms naturally over millions to billions of years within the Earth, while the other is grown in a laboratory in weeks or months.
Subtle distinctions can arise from their different growth environments. Natural diamonds often contain various inclusions and unique growth patterns formed by dynamic Earth conditions. For instance, natural diamonds can have tiny amounts of nitrogen, whereas some lab-grown diamonds, particularly CVD types, may have very low nitrogen content.
Lab-grown diamonds, due to their controlled growth, may exhibit different inclusion types or growth patterns detectable only with specialized equipment. HPHT diamonds can sometimes contain metallic inclusions from the catalyst used in their growth, and CVD diamonds may show small black carbon particles. The growth morphology can also vary, with natural diamonds often showing octahedral growth, while HPHT diamonds may display a combination of cubic and octahedral faces, and CVD diamonds typically grow with cubic faces. These microscopic differences are diagnostic for gemologists but do not alter the diamond’s fundamental nature or visible beauty.
Lab-Grown Diamonds and Simulants
It is important to differentiate lab-grown diamonds from diamond simulants. Lab-grown diamonds are real diamonds, pure crystallized carbon with the same atomic structure as natural diamonds. Simulants, however, are materials that only look like diamonds but have entirely different chemical compositions and physical properties. They are imitations designed to mimic a diamond’s appearance but are not diamonds themselves.
Common diamond simulants include cubic zirconia (CZ) and moissanite. Cubic zirconia is the cubic crystalline form of zirconium dioxide (ZrO₂). While CZ is hard, scoring around 8 to 8.5 on the Mohs scale, it is softer than a diamond and more prone to scratching and dulling. CZ also has a higher density, making a CZ stone of the same size heavier than a diamond. It exhibits a different refractive index and light dispersion, leading to a more rainbow-like sparkle compared to a diamond’s subtle brilliance.
Moissanite, another popular simulant, is composed of silicon carbide. Although moissanite is also very hard, typically scoring 9.25 on the Mohs scale, it is still slightly softer than a diamond. Moissanite also has a higher refractive index than diamond, which results in more “rainbow fire” or colorful flashes. Both cubic zirconia and moissanite are lab-created materials, but unlike lab-grown diamonds, they are not carbon-based diamonds.
How Lab-Grown Diamonds Are Identified
Distinguishing between natural and lab-grown diamonds requires specialized knowledge and equipment. While invisible to the naked eye, gemologists and appraisers use advanced tools to identify subtle markers related to their growth processes. These markers include specific internal growth patterns.
Microscopic characteristics, such as the shape and type of inclusions, can also provide clues. For example, HPHT-grown diamonds may contain tiny metallic inclusions from the growth catalyst, while natural diamonds might have mineral inclusions unique to their geological formation. Additionally, the way diamonds react to ultraviolet (UV) light, known as fluorescence, can offer insights. Lab-grown diamonds can fluoresce, often showing different patterns or intensities under UV light compared to natural diamonds.
Reputable gemological laboratories, such as the Gemological Institute of America (GIA) and the International Gemological Institute (IGI), play a crucial role in the identification and certification of lab-grown diamonds. These laboratories employ sophisticated spectroscopy and other techniques to detect minute differences in crystal structure or trace elements that reveal a diamond’s origin. Certified lab-grown diamonds are clearly labeled as such on their grading reports, providing consumers with transparent information.