Is a CZ Stud Just a Cheaper Diamond?
Summary
Cubic zirconia, shortened to CZ, is not diamond. GIA calls it a simulant: a stone that looks like diamond without having diamond’s chemical, physical and optical properties. A laboratory-grown diamond is different again. It is diamond, made in a laboratory instead of mined.
In studs, CZ gives a bright, colorless look at a lower price, and it lets you try a larger size without paying for diamond. The tradeoff is wear. GIA puts CZ at 8.5 on the Mohs scale, against 10 for diamond.
When you compare pairs, use the stone diameter in millimeters, then check the metal, setting, post, and backing. A label such as “one-carat look” tells you nothing on its own; look for the dimensions and a plain statement that the stone is CZ.
CZ is a look-alike, not a lower grade of diamond
GIA’s introduction to imitation gems describes simulants as materials, such as CZ, that look like another gem “but have very different chemical composition, crystal structure and optical and physical properties.” So mined diamond, laboratory-grown diamond, and CZ are three separate things to shop for.
The FTC’s advertising guidance asks for a word such as “imitation” or “simulated” in front of “diamond” when a stone only looks like one; our moissanite article covers that rule. If a listing says cubic zirconia, simulated diamond, or imitation diamond, take it at its word: it names a different stone, not a lower grade of diamond.
Why CZ can look so bright in stud earrings
GIA writes that “Most CZ can be described as colorless, and most have high clarity with minute, if any, imperfections,” and that “CZ has slightly more fire but less brilliance than diamond.” GIA also notes that “CZ will, however, yellow in color over time.”
In earrings, seen across a table instead of under a loupe, the colored flashes of that fire are what people notice. GIA’s comparison table notes that some people find these “broad flashes of color” artificial. Others like them.
Use millimeters to compare size
GIA’s carat page puts it in five words: “Carat measures weight, not size.” The same GIA article on simulants explains that they “have varying densities (weight to volume ratio),” so a simulant and a diamond of the same carat weight need not look the same size.
For studs, the millimeter diameter tells you how much of the earlobe the stone covers. A 6 mm stone is only 1 mm wider than a 5 mm stone, but its face is about 1.44 times larger (6 × 6 against 5 × 5).
The setting and backing can change how the stud wears
A large stud can tilt forward if the setting is heavy and the backing is small. Jewelers of America calls friction or push backs “the most common” and warns that “Over time, these backs can loosen, get lost, or allow the earring to slip off the ear.” It adds that “the larger the diameter, the more secure the clasp.”
Read the metal of the post and back as a separate item from the stone. CZ can be set in sterling silver, gold alloy, stainless steel, plated metal, or another material. For sensitive ears, the post metal is the part to read about, and the sensitive-ears guide covers it.
Which one makes sense for you?
CZ makes sense when the look, size, and price come first. Diamond makes sense when owning diamond, long-term scratch resistance, or grading information is part of what you want. GIA’s article on simulants adds that “Natural diamonds will also retain more value than diamond simulants.”
Looking for a piece? Browse earrings in the feed →
Sources
- GIA, Diamond Carat Weight
- GIA, What Are Simulated Diamonds?
- GIA, An Introduction to Imitation Diamonds & Other Gems
- Jewelers of America, Earring Style Guide
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