How To Tell Cubic Zirconia From Diamond?

At Siebke Hoyt, with our storied history dating back to 1889, we understand the allure and significance of fine gemstones. A question we often encounter is how to differentiate between cubic zirconia and diamonds. Whether you're selecting a new piece of jewelry or assessing a family heirloom, this knowledge is invaluable. Our guide, backed by our experienced and knowledgeable staff, aims to demystify this process.

Background Information

Cubic Zirconia vs. Diamond: What's the Difference?

Diamonds, a symbol of luxury and durability, are famed for their natural origin and impressive hardness. Cubic zirconia, on the other hand, is a synthetic alternative that offers a diamond-like appearance at a fraction of the cost. Both have their unique appeal and uses in the jewelry world.

Physical Properties

A Comparative Look

To the untrained eye, these stones may appear similar, but their physical properties reveal key differences:

  • Hardness: Diamonds rank a 10 on the Mohs scale, the highest for any material, whereas cubic zirconia is around 8-8.5.
  • Brilliance and Refractive Index: Diamonds have a unique brilliance due to their high refractive index. Cubic zirconia, although sparkly, has a different pattern of light dispersion.
  • Color and Clarity: Diamonds vary in color and clarity, but cubic zirconia is usually flawless and colorless, mimicking the look of a high-quality diamond.
  • Weight and Density: Cubic zirconia is denser and heavier than diamonds of the same size.

Tests to Differentiate

Simple Methods to Identify

You don't need to be a gemologist to perform these basic tests:

  • Visual Inspection: Look for signs of wear and tear; cubic zirconia scratches more easily than diamond.
  • The Fog Test: Breathe on the stone. A diamond's heat dispersal clears the fog quickly, whereas cubic zirconia does not.
  • The Scratch Test: Exercise caution, as this can damage the stone.
  • Professional Appraisal: Our skilled staff at Siebke Hoyt, with an average tenure of eight years, can assist with professional evaluations. Make An Appointment.

Market Considerations

Understanding Value and Appeal

Diamonds are generally more expensive and hold value over time, whereas Cubic zirconia offers an affordable alternative for fashionable designs. We believe in providing quality merchandise at a fair price, be it diamond or cubic zirconia.

Maintenance and Care

Preserving the Sparkle

  • Cubic Zirconia: Regular cleaning with mild soap and water keeps it shining.
  • Diamonds: Require professional cleaning to maintain their brilliance. Contact Us for advice on diamond care.


Discerning between cubic zirconia and diamonds can be simple with the right information. At Siebke Hoyt, we're committed to guiding you through this process, showcasing our family-owned business's philosophy of honesty and quality. Whether you're a seasoned collector or a first-time buyer, our friendly staff is here to help.

For more insights into the fascinating world of gemstones, visit our Blog. Our legacy, coupled with the expertise of our staff, makes Siebke Hoyt your trusted partner in all things jewelry.