A practical guide for jewelry lovers to distinguish between diamonds and cubic zirconias

Synthetic cubic zirconia, the perfect “diamond” substitute, is the best diamond imitation in the jewelry industry, which provides the jewelry market with a variety of high-quality and inexpensive jewelry to beautify our lives, and even some jewelry sellers have mistaken cubic zirconia for diamonds. Even some jewelry sellers have mistaken cubic zirconia for diamonds. There is a lot to learn about distinguishing synthetic cubic zirconia from diamonds.

What is synthetic cubic zirconia?

Synthetic cubic zirconia (CZ) is a synthetic gemstone material composed primarily of cubic zirconia (ZrO₂). While natural cubic zirconia is very rare, synthetic cubic zirconia is very similar to natural diamonds in terms of physical properties, making it one of the most popular alternatives to diamonds.

Physical Properties

Hardness: Synthetic Cubic Zirconia has a Mohs hardness of approximately 8.5, which is lower than diamond (10) but is still a very hard material that is resistant to everyday wear and tear.
Refractive index: CZ has a refractive index (2.15-2.18) close to that of diamond (2.417), which makes it visually similar to diamond, with good luster and scintillation.
Dispersion: CZ has a high dispersion (0.058-0.066), higher than that of diamonds (0.044), which means it tends to be more colorful than diamonds.

Production Methods

Synthetic cubic zirconia is usually produced by a fusion process. In this process, zirconia powder is melted at high temperatures and then slowly cooled to form single crystals. The CZ crystals produced by this method are colorless and transparent, or colored CZ can be produced by adding different elements.

Application Scenarios

Jewelry: Due to its low cost and diamond-like appearance, CZ is widely used in a variety of jewelry, such as rings, necklaces, and earrings.
Fashion accessories: CZ is also commonly used to make low-cost fashion accessories for daily wear or special occasions.
Decorations: In addition to jewelry, CZ is also used for decorations, such as embellishments on small objects such as phone cases and keychains.
Difference with natural diamonds
Weight: CZ is about 1.5 times lighter than diamonds, which means that CZ of the same size is lighter than diamonds.
Hardness: Although CZ is very hard, it is still not as hard-wearing as diamonds and may show minor scratches over time.
Value: Since CZ is man-made, its market value is much lower than that of a natural diamond.
Identification: Although it is difficult to distinguish between CZ and diamonds with the naked eye, a professional jewelry appraiser can identify the two by looking through a microscope or using specialized testing equipment.
Distinguishing diamonds from synthetic cubic zirconia (CZ) can be a bit challenging for the layman, as they have a high degree of similarity in appearance. However, it is possible to distinguish between the two by careful observation and using some simple tests.

Here are some practical ways to help you distinguish between diamonds and synthetic cubic zirconia:

Magnifying Glass Inspection:

Use a 10x magnifying glass to look at the surface and internal features of the stone. Diamonds usually have some naturally occurring inclusions or blemishes, while CZ is flawless.
If noticeable bubbles, streaks or other unnatural features are found, it is most likely a CZ.

Brilliance and Scintillation:

Diamonds have a very distinctive luster and scintillation, especially in the light, with an intense white glow and a rainbow of color dispersion.
While CZ can also produce scintillation, its dispersion (rainbow of colors) tends to be more pronounced than diamonds.

Surface Texture:

The surface of a diamond may show some minor texture or abrasions from the cutting and polishing process, whereas the surface of CZ is smoother and more even.
Testing Methods

Fogging Test:

Gently breathe into the stone and if the surface quickly fogs up and then quickly returns to clarity, it is most likely a diamond, as diamonds conduct heat very well.
Conversely, if the fogging of the surface lasts longer, it is likely to be a CZ, which has poor thermal conductivity.

Scratch Test:

While a scratch test on an unknown stone is not recommended, if conditions permit and you are certain that no damage will result, try gently scratching the surface of the stone with another small, known diamond.
Diamonds are the hardest natural substance and will not be scratched by anything else; CZ, while also hard, could theoretically be scratched by a diamond.

Thermal Conductivity Meter Test:

Use a specialized thermal conductivity meter to test the gemstone. Diamonds are excellent conductors of heat, while CZ has relatively poor thermal conductivity.
This method is one of the most accurate ways to differentiate between diamonds and CZ, but requires specialized equipment.
Other methods

Specific Gravity Test:

Although uncommon, it is also possible to distinguish between the two by measuring the specific gravity (density) of a gemstone. Diamonds have a specific gravity of about 3.52 g/cm³, while CZ has a specific gravity of about 5.65 g/cm³.
Different specific gravities mean that they will sink at different rates in water or density liquids.

Professional Identification:

The most reliable way to have a gemstone tested is to take it to a professional jewelry appraiser. They have the specialized tools and experience to accurately identify the type of gemstone.
Precautions.

Before performing any tests, make sure you do not permanently damage the gemstone.
Try not to perform a scratch test without confirmation to avoid damaging the precious gemstone.
The safest method is to consult a professional jewelry appraiser or gemologist.

Although diamonds and synthetic cubic zirconia have a high degree of similarity in appearance, it is still relatively easy to distinguish between them by the methods described above. If you’re not sure what gemstone you have in your hands, the safest course of action is to seek professional appraisal services!