A “fake diamond” is a diamond simulant, a material that mimics the visual appearance of a natural diamond without sharing its chemical composition or crystal structure. These substitutes are cut and polished to achieve a diamond-like sparkle, offering a substantially more affordable alternative for the jewelry market. Simulants possess entirely different physical and optical properties, such as hardness, density, and the way they disperse light. The search for materials that imitate the brilliance of a diamond has led to the development of several distinct substances.
The Reigning King of Simulants: Cubic Zirconia
The most widely recognized diamond simulant is Cubic Zirconia (CZ). This material is a synthesized crystalline form of Zirconium Dioxide, which requires a stabilizer to maintain its cubic structure at room temperature. Commercial production began in the mid-1970s, quickly establishing CZ as the dominant affordable diamond alternative.
CZ is popular because it offers a close visual likeness to a diamond at a fraction of the cost. Its physical properties, however, clearly distinguish it. It registers at 8 to 8.5 on the Mohs scale of hardness, making it noticeably softer than a natural diamond’s perfect 10. This lower hardness means the surface of a CZ stone is more prone to scratching and abrasion, which can dull its initial brilliance over time.
One of the most telling characteristics of CZ is its optical performance, particularly its dispersion, which is the separation of white light into spectral colors, often called “fire.” Cubic Zirconia has a very high dispersion rate (0.058 to 0.066), which significantly exceeds a diamond’s value of 0.044. This results in an exaggerated, rainbow-like sparkle that can appear less subtle than the fire found in a natural diamond. Furthermore, Cubic Zirconia is approximately 1.7 times denser than diamond, meaning a stone of the same diameter and cut will weigh significantly more.
The Modern Contender: Moissanite
Moissanite has emerged as a premium simulant, often considered superior to Cubic Zirconia due to its closer physical properties to diamond. The material is composed of Silicon Carbide, a compound exceedingly rare in nature and primarily found in meteorites. Virtually all gem-quality moissanite is synthesized in a laboratory, with production perfected in the late 1990s to offer a durable and visually striking alternative.
The hardness of moissanite is remarkably high, ranking at 9.25 on the Mohs scale, second only to diamond. This exceptional durability makes it highly resistant to scratching and ideal for daily wear. Moissanite also possesses a higher refractive index than diamond (2.65 and 2.69), which contributes to its intense brilliance.
Moissanite’s dispersion is notably higher than a diamond’s, registering at 0.104, which is more than double the diamond value. This heightened fire creates a distinct, colorful flash, sometimes described as a “disco-ball” effect. Moissanite also has high thermal conductivity, a property it shares with diamond, which can cause it to pass basic diamond testing devices that rely solely on heat as a distinguishing factor.
Other Historical and Lesser-Known Substitutes
Before the rise of modern simulants, other materials were used to imitate diamonds, though most are now obsolete in fine jewelry. One of the earliest forms of imitation was glass, often referred to as paste or rhinestones, which were faceted to catch the light. Glass is exceptionally soft, registering only about 5.5 on the Mohs scale, making it highly susceptible to wear and scratches.
Other synthetic materials were developed in the mid-20th century, serving as transitional simulants. Strontium Titanate was popular in the 1950s, prized for its high refractive index, which nearly matched that of diamond. However, its extreme dispersion of 0.190 created excessive fire, and its low hardness (only 5 to 5.5 on the Mohs scale) led to rapid replacement due to poor durability. Yttrium Aluminum Garnet (YAG) was another synthetic crystal used as a substitute in the 1960s and early 1970s. YAG offered improved hardness (around 8.25), but its low dispersion of 0.028 resulted in a lack of fire, making it less convincing than later simulants.
The Important Distinction: Not All Lab Creations Are Fake
It is important to understand the significant difference between a diamond simulant and a synthetic, or lab-grown, diamond. Simulants are materials with a completely different chemical makeup than diamond, such as zirconium dioxide or silicon carbide. They merely look like diamonds but do not share their properties.
In contrast, a lab-grown diamond is a genuine diamond, sharing the exact same chemical composition, crystal structure, and physical properties as a mined diamond. Both are pure, crystallized carbon, created under high pressure and high temperature, or through chemical vapor deposition. The only distinction lies in their origin: one is formed beneath the Earth’s crust, and the other is grown within a controlled laboratory environment. Therefore, while simulants are imitations, a lab-grown diamond is a real diamond and is not considered “fake.”