A diamond is a solid form of the element carbon, distinguished by its atoms being arranged in a specific crystal structure known as diamond cubic. This precise, tightly bonded lattice gives the mineral its famed physical properties, including unparalleled hardness and exceptional optical qualities. Diamonds were first discovered and mined in India, where they were revered as sacred objects and ornaments. Today, the diamond’s brilliance and durability make it a universally recognized symbol of commitment and lasting value.
The Origin and Composition of Natural Diamonds
Natural diamonds form deep within the Earth under extreme geological conditions. They are typically born in the mantle, at depths between 90 and 150 miles below the surface. Here, immense heat (1,650 to 2,370 degrees Fahrenheit) and pressure (45,000 to 60,000 times atmospheric pressure) cause pure carbon atoms to crystallize into the tetrahedral structure of a diamond.
Most natural diamonds are ancient, ranging from one billion to 3.5 billion years old. Their journey to the surface is swift, carried up by rare, deep-source volcanic eruptions through columns of rock called kimberlite pipes. This rapid ascent prevents the diamonds from reverting to graphite, which is the more stable form of carbon under lower pressure. A natural diamond is chemically almost pure carbon, and its characteristic internal arrangement defines what a “real” diamond truly is.
Distinguishing Real Diamonds from Simulants
The term “diamond simulant” refers to any material that mimics the appearance of a diamond but possesses a different chemical composition and crystal structure. Two common simulants are Cubic Zirconia (CZ) and Moissanite. Cubic Zirconia is a synthesized material made of zirconium dioxide, which is significantly softer than a diamond, ranking around 8 on the Mohs scale compared to a diamond’s 10. CZ also has a lower refractive index, meaning it handles light differently and can appear less brilliant or develop a cloudy appearance over time.
Moissanite is a compound of silicon carbide and scores 9.25 on the Mohs scale, making it a durable alternative. Moissanite is identifiable by its distinct optical properties, including a much higher refractive index and greater light dispersion than diamond. This higher dispersion causes moissanite to exhibit a strong “fiery” or rainbow-colored flash, which is more pronounced than the white brilliance of a diamond. Furthermore, moissanite is doubly refractive, meaning light entering the stone is split into two rays, causing the back facets to appear slightly doubled under magnification.
Lab-Grown Diamonds: The Key Difference
Lab-grown diamonds, often called synthetic or cultured diamonds, are physically, chemically, and optically identical to natural diamonds. Unlike simulants, a lab-grown diamond is composed of pure carbon atoms arranged in the same diamond cubic structure, making it a true diamond in every scientific sense. The only difference is their origin: they are manufactured in a controlled laboratory environment over weeks rather than forming naturally over millions of years.
The two primary manufacturing methods are High-Pressure/High-Temperature (HPHT) and Chemical Vapor Deposition (CVD). The HPHT process replicates the Earth’s mantle conditions by placing a diamond seed and carbon material into a chamber exposed to extreme heat and massive pressures. The CVD method involves heating a diamond seed in a sealed chamber while introducing carbon-rich gases, like methane. These gases break down into plasma, releasing carbon atoms that deposit layer by layer onto the seed, allowing the diamond to grow.
Practical Tests for Identification
Distinguishing a diamond from a simulant or a lab-grown stone uses a combination of consumer tests and specialized professional equipment. The high thermal conductivity of a diamond—its ability to quickly disperse heat—is reliable for separating it from simulants like Cubic Zirconia. The simple “fog test” demonstrates this: condensation formed by breathing on a genuine diamond clears almost instantly, but lingers longer on a simulant. Jewelers use electronic thermal conductivity testers based on this principle, which are effective against most simulants.
Traditional thermal testers cannot distinguish a diamond from moissanite because moissanite is also an efficient heat conductor. Therefore, professional jewelers must use specialized instruments that measure electrical conductivity or specific optical properties to reliably identify moissanite. Distinguishing a natural diamond from a lab-grown diamond is the most nuanced challenge, requiring advanced equipment like UV fluorescence analysis or high-power magnification. These tools detect subtle differences in crystal growth patterns or trace element inclusions unique to either a natural or manufactured origin.