What is Cubic Zirconia? Guide to Its Value and Properties

You've seen it on fingers, in earrings, and around wrists. Cubic zirconia is one of the most used gemstones in jewelry today, yet most people know surprisingly little about it. What's it made of? Does it tarnish? How much is it actually worth? From fine jewelry to silicone rings designed for active lifestyles, CZ turns up everywhere.

So, in this guide, we’ll cover its properties, real value, and how to care for it.

Key Takeaways

• Cubic zirconia is a lab-created gemstone — not a mined stone, and not the same as zircon.

• Its value comes from beauty and accessibility, not investment potential — and the grade scale explains why some CZ sparkles more than others.

• The stone itself doesn't tarnish, but your setting material is the real variable.

• CZ is hypoallergenic, though the metal it's set in may not be — metal choice matters more than most people realize.

• Dullness and tarnish are not the same thing — restoring a CZ stone's sparkle is simpler than most care guides suggest.

• Black cubic zirconia plays by the same rules (same hardness, same care), just a bolder aesthetic.

What Is Cubic Zirconia?

Cubic zirconia is a synthetic gemstone made from zirconium dioxide (ZrO₂), first produced commercially in 1976. All CZ used in jewelry today is lab-grown. Natural cubic zirconia does exist, but it is so rare that it plays no part in the gem market.

One distinction worth making: CZ is not zircon. Zircon is a natural mineral (zirconium silicate) with different properties entirely. The shared name causes confusion, but they are completely separate stones.

The word "cubic" refers to its crystalline structure. Diamonds share this same form, which is the main reason a well-cut cubic zirconia gemstone can closely resemble a diamond to the naked eye.

At a glance:

What Is Cubic Zirconia Made Of?

Production starts with zirconium oxide powder mixed with a stabilizer, typically yttrium oxide or calcium oxide. This prevents the material from forming unstable crystals. The mixture is then heated to around 5,000°F using skull melting, where the outer layer acts as its own container. As it cools, cubic crystals form and are later cut into shape.

Color is introduced by adding trace rare-earth elements during synthesis, a technique called doping. This is how the full range of CZ colors is produced. Black cubic zirconia, for example, gets its opaque, jet-dark finish from specific metallic oxide additions during the growth phase. Our black cubic zirconia silicone ring is a good example of how an affordable, flexible-base ring lets you wear a striking CZ stone daily, with a sterling silver bezel that keeps it secure and polished through an active lifestyle.

How Much Is Cubic Zirconia Worth?

Honestly, very little in monetary terms. A 1-carat diamond of good quality can retail for thousands of dollars. A comparable cubic zirconia stone costs a few dollars at most and carries essentially no resale value.

That framing, though, misses the point. CZ's value is in what the wearer gets — consistent clarity, real sparkle, and no ethical concerns tied to mined stones.

What separates a dull CZ from a brilliant one is grade. Stones are rated on a scale from AB to 5A:

When shopping, grade matters more than carat size. A smaller 5A stone will outshine a larger AB every time.

Does Cubic Zirconia Tarnish?

No, the stone itself cannot tarnish. Tarnish is a chemical reaction that happens when metals oxidize. Since cubic zirconia is a pure synthetic oxide with no metallic content, it simply has no chemistry that allows this to occur.

What people often mistake for tarnish is dullness — a thin film of skin oils, lotion, and everyday residue sitting on the stone's surface. It blocks light. It kills sparkle. But it's reversible.

The real tarnish risk sits in the setting, not the stone:

• Base metals (copper and brass alloys) oxidize and can discolor the skin.

• Sterling silver can dull over time, but won't react with skin the way base metals do.

• Gold and platinum are the most stable long-term options.

So when cubic zirconia jewelry looks dull, check the setting first. The stone is almost never the problem.

Is Cubic Zirconia Hypoallergenic?

Yes. As a pure synthetic crystal, a cubic zirconia gemstone contains no nickel, no copper, and no reactive metals — none of the materials that typically trigger skin reactions. The stone itself is a safe choice for sensitive skin.

The metal setting is a different story. Reactions people attribute to CZ jewelry are almost always caused by what the stone sits in, not the stone itself. Nickel is the most common cause.

What to look for when buying:

• Sterling silver — nickel-free, widely tolerated, great for everyday wear.

• 14K gold and above — stable and skin-friendly.

• Platinum — the most hypoallergenic metal option available.

• Avoid — plated alloys and brass-based settings, especially for rings worn daily.

For active wear, where the ring stays on through workouts and daily tasks, a flexible silicone base with a sterling silver bezel gives you that skin-safe, comfortable fit without sacrificing the look of a real stone.

How Do You Make Cubic Zirconia Sparkle?

Clean it. Dullness is surface buildup — oils, residue, and everyday grime sitting on the facets. Remove that layer, and the sparkle returns.

The Cleaning Routine

1. Mix warm water with a few drops of mild dish soap.

2. Use a soft toothbrush to gently scrub the stone.

3. Pay attention to the underside. Residue collects beneath the setting and blocks light from below.

4. Rinse thoroughly, then pat dry with a lint-free cloth.

Most guides skip step three. It makes the biggest difference.

What to Avoid

• Harsh chemicals, bleach, or alcohol-based cleaners.

• Ultrasonic cleaners — they can loosen settings over time.

• Baking or heat treatments (a common DIY myth that can crack or discolor the stone).

Our full collection features hand-set stones in sterling silver bezels — an open-back design that makes this cleaning routine quick and straightforward.

What Makes Black Cubic Zirconia Stand Out?

Simple: it doesn't look like a diamond imitation. Where clear CZ draws comparison to diamonds, black cubic zirconia has its own identity — opaque, deep, and distinctly modern.

The aesthetic is versatile in a way few stones are. Black reads as bold without being loud. It pairs with everything, works for any occasion, and doesn't demand a dressy outfit to look intentional.

Beyond the look, nothing changes under the hood:

• Same 8–8.5 Mohs hardness as standard CZ

• Same cleaning routine — warm water, soft brush, done

• Same setting compatibility — sterling silver bezels suit it particularly well

For anyone who wants a ring that holds up through an active day and still looks polished, a black cubic zirconia set on a flexible silicone base is one of the most practical choices available.

The Honest Case for Cubic Zirconia

Cubic zirconia stands on its own merits. A lab-created gemstone with real properties, consistent quality, and genuine sparkle — one that costs a fraction of what a diamond does. For everyday wear, especially in a setting designed to move with you, that combination is hard to argue with. Know the grade, choose the right metal, keep it clean. That's genuinely all it takes to get years of wear out of a stone that earns its place in any jewelry collection.