When exploring what comes closest to a diamond, “closest” can refer to properties like visual appearance, hardness, brilliance, or chemical makeup. Various materials offer characteristics similar to diamonds, each with its own advantages and differences. Understanding these distinctions clarifies why certain gems or materials are considered alternatives.
Diamond Simulants
Diamond simulants visually resemble diamonds but possess entirely different chemical, physical, and optical properties. These substances are not actual diamonds; they merely imitate their appearance. Common examples include Cubic Zirconia (CZ), Moissanite, and white sapphire.
Cubic Zirconia (CZ) is a synthetic material composed of zirconium dioxide, a popular and affordable diamond alternative. It has a hardness of 8 to 8.5 on the Mohs scale, making it less resistant to scratching than a diamond. Unlike diamonds, CZ displays a more pronounced rainbow-like “fire” and has a lower refractive index (2.15-2.18) compared to diamond’s 2.42. It is singly refractive, meaning light passes through it in a single ray.
Moissanite is a silicon carbide material, typically lab-grown due to the extreme rarity of natural moissanite. It is remarkably hard, scoring 9.25 to 9.5 on the Mohs scale, second only to diamond. Moissanite exhibits a higher refractive index (2.65-2.69) than diamond, resulting in greater brilliance and more intense colorful flashes, often described as a “disco ball” effect. Its double refraction, where light splits into two rays, is a distinctive characteristic observable under magnification.
White sapphire is a colorless variety of the mineral corundum, aluminum oxide. It ranks 9 on the Mohs hardness scale, durable for everyday wear. However, white sapphire has a lower refractive index (1.76-1.77) compared to diamond, leading to less brilliance and fire. This results in a softer, more muted sparkle, and it may appear “watery” or “hazy” without frequent cleaning. Like moissanite, white sapphire is also a doubly refractive gemstone.
Lab-Grown Diamonds
Lab-grown diamonds are real diamonds, identical in chemical, physical, and optical properties to natural diamonds. Their sole difference is origin: they are created in a controlled laboratory environment from crystallized carbon, rather than being mined.
Their creation typically involves two primary methods: High-Pressure/High-Temperature (HPHT) and Chemical Vapor Deposition (CVD). The HPHT method mimics the natural diamond formation process by subjecting a carbon seed to extreme heat and pressure. The CVD method involves placing a diamond seed in a vacuum chamber with carbon-rich gases, allowing carbon atoms to build up layer by layer. Both processes yield diamonds visually indistinguishable from mined diamonds without specialized equipment.
Consumers often choose lab-grown diamonds for various reasons, including their lower cost compared to natural diamonds of similar quality. They also offer traceability and can address ethical or environmental concerns associated with traditional mining.
Key Distinctions and Identification
Distinguishing natural diamonds, lab-grown diamonds, and simulants relies on their unique physical and optical properties. Natural and lab-grown diamonds share a Mohs hardness of 10, making them the hardest known materials and highly resistant to scratching. In contrast, moissanite scores 9.25-9.5, white sapphire 9, and cubic zirconia 8-8.5 on the Mohs scale, indicating they are softer and more prone to wear over time.
Refractive index, governing a stone’s brilliance, also varies significantly. Diamonds have a refractive index of 2.42, while moissanite is higher at 2.65-2.69, and cubic zirconia is lower at 2.15-2.18. White sapphire has a considerably lower refractive index of 1.76-1.77. This difference in light bending causes moissanite to exhibit more “fire” or rainbow flashes than a diamond, a noticeable characteristic. Cubic zirconia also shows more rainbow flashes than diamond, especially in larger sizes.
Thermal conductivity provides another distinguishing factor. Diamonds are excellent thermal conductors, utilized by most diamond testers. These devices measure how quickly heat moves through a stone, giving a positive reading for diamonds and moissanite, both good heat conductors. However, cubic zirconia acts as a thermal insulator, producing a negative result on thermal testers.
Specialized electrical conductivity testers differentiate moissanite from diamond, as moissanite conducts electricity while diamond does not. Visual inspection can also reveal differences; for instance, moissanite’s double refraction can cause a “doubling” effect of facet edges under 10x magnification. Diamonds typically have sharp, crisp facet edges, whereas simulants like CZ may develop rounded edges with wear.