Diamond vs Cubic Zirconia
In the world of fine jewelry, diamonds are considered the gold standard for their sheer brilliance and timelessness. Whether set on an engagement ring, a pair of earrings, or on a heirloom pendant, diamonds are the embodiment of luxury and cherished sentiments.
With their practically universal appeal, there are many alternatives in the jewelry industry that try to mimic the look of a natural diamond. Among the most notable is cubic zirconia (CZ).
While they may look the same to the untrained eye, diamonds, and cubic zirconia are remarkably different, from composition and visual properties to long-term value.
In this article, we’ll give a breakdown of the key differences between the two gemstones so if you ever find yourself deciding between each, you can make an informed decision.
Chemical Composition and Formation
Diamonds
Diamonds are natural gemstones formed deep within the Earth’s mantle. Composed of pure carbon atoms arranged in a diamond cubic crystal lattice, they are subjected to extreme heat and pressure for millions and even billions of years, making diamonds one of the oldest substances on Earth.
The unique crystal structure of diamonds is the product of carbon atoms bonding in a tetrahedral arrangement. This gives diamonds their hardness and thermal conductivity.
Natural diamonds can contain impurities or structural defects in the crystal lattice, and thus can even appear in different colors.
Cubic Zirconia
In contrast to natural diamonds, cubic zirconia is a synthetic gemstone. It’s composed of zirconium dioxide (ZrO₂) stabilized with small amounts of other metal oxides – typically yttrium oxide. The name “cubic zirconia” refers to the same cubic crystal structure found in diamonds.
Cubic zirconia was first synthesized in the 1930s. However, it wasn’t produced in gem quality until the 1970s. The manufacturing process involves melting zirconium oxide powder with stabilizers at temperatures above 2,700°C. As the material cools, it crystallizes into a cubic structure to form the final product.
Physical Properties: Hardness and Durability
One of the most notable differences between diamonds and cubic zirconia is their hardness and durability.
Diamonds are famous for being the hardest known natural substance. Measuring a 10 on the Mohs scale of mineral hardness, this is what gives diamonds their unparalleled durability and scratch resistance. This characteristic is particularly valuable in everyday jewelry, such as an engagement ring.
Cubic zirconia measures around 8 to 8.5 on the Mohs scale – harder than most other gemstones, but considerably softer than diamonds. Therefore, cubic zirconia is more prone to scratching and wear over time. It can also lose its brilliance and even appear cloudy after prolonged wear, especially when exposed to oils or dirt.
Optical Properties: Refractive Index and Dispersion
When comparing gemstones, we must also take into consideration optical properties such as how they appear in and interact with light.
With a refractive index of 2.417 – 2.419 , diamonds are incredibly bright and brilliant. The dispersion rating of diamonds, or how much white light is split into its many colors, is 0.044.
Cubic zirconia has a refractive index of 2.15-2.18. This gives it a different kind of brilliance from diamonds. Its dispersion rating is 0.060, which means the stone gives more color separation and a greater “rainbow effect” when light passes through it; in essence, it looks more fiery and has more intense color flashes than natural diamonds.
This light performance can be so intense to the point where it makes the stone look artificial. This becomes especially apparent when a cubic zirconia stone is compared directly to the more subtle light performance of natural diamonds.
Color and Clarity
Color Variations
Mined diamonds are formed in nature, and come in many colors – from colorless to yellow, brown, pink, blue and even black. The most valuable diamonds are usually colorless, with the exception of those with rare or intense natural colors. The natural color of a diamond is graded from D (colorless) to Z (light yellow or brown).
Cubic zirconia, being synthetic, can be made in any color by adding different materials during the manufacturing process. Though, it’s most commonly made to imitate colorless diamonds.
Clarity and Inclusions
Natural diamonds often have internal features called inclusions, which are remnants of the crystal’s growth process. These can be other minerals, fractures or even tiny diamonds within the larger stone. Inclusions of a given stone are measured by its clarity grade. Clarity is graded on a scale from Flawless (no inclusions or blemishes visible under 10x magnification) to Included (inclusions visible to the naked eye).
Cubic zirconia is usually flawless and inclusion free. In addition to its brilliance and fire, the flawless clarity of CZ can sometimes be a giveaway that a stone is indeed CZ and not a natural diamond.
Although cubic zirconia stones come flawless from the lab, unlike diamonds, because of their lesser hardness, over time these stones can become faded, cloudy, or chipped depending on wear.
Investment Considerations
The value of diamonds is mainly driven by their rarity and the effort involved in extracting them. Natural diamonds, especially high-quality ones, are scarce resources that require a lot of effort and investment to mine. This scarcity combined with market demand and marketing strategies is what make diamonds so expensive.
Cubic zirconia, on the other hand, can be produced in large quantities and at a very low cost. This abundance and ease of production sets its market value much lower than diamonds.
Conclusion
To the untrained eye, diamonds and cubic zirconia may look remarkably similar. However, the two materials are fundamentally different and exhibit different properties and values. With a lifetime spanning millions and billions of years, diamonds offer unparalleled hardness, unique optical performance and cultural value. Cubic zirconia, on the other hand, offers an alternative that gives off an aesthetic that’s a little on the artificial side, but nonetheless is still sparkly and brilliant at a fraction of the cost.
The choice between the two comes down to individual preference, values and budget. Whether you’re looking for the classic charm of a natural diamond or are in need of something that’s to be part of a costume piece, the choice between diamond and cubic zirconia ultimately depends on the situation at hand.