How to Tell Cubic Zirconia from Diamond?

Cubic zirconia (CZ) and diamonds may appear similar at first glance, but they are quite different in terms of composition, value, and properties. At Plateau Jewelers in Sammamish, WA, we often help customers understand these differences to make informed choices. This guide will walk you through the key indicators that can help you distinguish cubic zirconia from diamond, ensuring that you know what you’re buying or evaluating.

History and Production

History of Cubic Zirconia

Cubic zirconia was first synthesized in the 1970s and quickly gained popularity as a diamond simulant. Its affordability and diamond-like appearance made it a popular choice for costume jewelry. By the 1980s, CZ had become widely used in a variety of jewelry pieces, from rings and earrings to necklaces and bracelets. Its flawless clarity and colorless quality made it an attractive alternative to more expensive diamonds.

Diamond Mining and Creation

Natural diamonds are formed over billions of years under intense heat and pressure deep within the Earth's mantle. These precious gems are brought to the surface through volcanic eruptions and are then mined from kimberlite pipes and alluvial deposits. The journey of a natural diamond from the Earth to a piece of jewelry involves extensive cutting and polishing to enhance its brilliance and fire.

Visual Inspection

Brilliance and Fire

  • Diamonds: Known for their exceptional brilliance, diamonds reflect light in a way that creates a dazzling sparkle. This is due to their high refractive index and the quality of their cut. Diamonds also display "fire", which is the dispersion of light into various colors.
  • Cubic Zirconia: While CZ also has impressive brilliance, it tends to exhibit a more intense, rainbow-like sparkle compared to the subtler fire of a diamond. This difference can be noticeable under direct light, where CZ can appear "too perfect" or overly colorful.

Color and Clarity

  • Diamonds: Diamonds come in a range of colors, from completely colorless to shades of yellow and brown. They can also have inclusions (internal flaws) or blemishes (surface flaws), which affect their clarity.
  • Cubic Zirconia: CZ is typically flawless and colorless. High-quality CZ stones are manufactured to be free of inclusions and are often more perfectly clear than most diamonds.

Physical Properties

Hardness

  • Diamonds: Diamonds are the hardest known natural material, scoring a 10 on the Mohs scale of hardness. This exceptional hardness makes them resistant to scratches, maintaining their polish and brilliance over time.
  • Cubic Zirconia: CZ is significantly softer, scoring about 8.5 on the Mohs scale. This means CZ can be scratched more easily, leading to a loss of luster and visible wear over time.

Weight

  • Diamonds: Diamonds are denser than cubic zirconia. This density difference means that a diamond will weigh less than a CZ of the same size.
  • Cubic Zirconia: CZ is about 1.7 times denser than diamond. If you compare two stones of identical dimensions, the CZ will feel heavier in your hand.

Professional Testing

Thermal Conductivity

  • Diamonds: Diamonds are excellent conductors of heat. A diamond tester, which measures thermal conductivity, will quickly identify a real diamond because heat passes through it rapidly.
  • Cubic Zirconia: CZ is a poor conductor of heat. A diamond tester will indicate that CZ is not a diamond due to its slow heat dissipation.

Electrical Conductivity

  • Diamonds: Some advanced testers measure electrical conductivity to differentiate between diamond and CZ. Diamonds conduct electricity to a certain extent, which can be detected by these specialized tools.
  • Cubic Zirconia: CZ does not conduct electricity like diamonds do, allowing testers to distinguish between the two materials.

Examination Techniques

Loupe Examination

Using a jeweler's loupe, you can inspect the stone for characteristics that differentiate diamonds from CZ:

  • Facet Edges: The facet edges on a diamond are usually sharper and more precise. CZ tends to have slightly rounded facet edges due to its lower hardness.
  • Inclusions: Under magnification, diamonds may show natural inclusions or blemishes. CZ is typically flawless, which is a telltale sign when examined closely.

Fog Test

The fog test is a simple way to differentiate between diamond and CZ:

  • Diamonds: When you breathe on a diamond, the fog from your breath will dissipate almost immediately due to the diamond’s thermal conductivity.
  • Cubic Zirconia: CZ will hold the fog for a few seconds longer because it doesn’t conduct heat as efficiently.

UV Light Test

Under UV light, some diamonds will emit a blue fluorescence. However, this test is not definitive as not all diamonds fluoresce, and some CZ stones may also emit fluorescence. It can be an additional tool, but not a standalone test.

Common Uses and Popularity

Jewelry Applications

  • Diamonds: Known for their durability and unmatched brilliance, diamonds are used in a wide range of jewelry. They are the go-to choice for engagement rings, wedding bands, earrings, necklaces, and bracelets. Diamonds are prized for their ability to withstand everyday wear while maintaining their sparkle.
  • Cubic Zirconia: CZ is commonly used in fashion and costume jewelry due to its affordability and diamond-like appearance. It is often set in rings, earrings, pendants, and bracelets. CZ is a popular choice for those who want the look of diamonds without the high cost, making it ideal for statement pieces and trend-driven designs.

Popularity Trends

  • Diamonds: The timeless appeal of diamonds has kept them at the forefront of fine jewelry for centuries. Their association with love, commitment, and luxury makes them a preferred choice for significant life events, such as engagements and anniversaries. Economic factors and cultural trends also influence the popularity of diamonds, with shifts in consumer preferences towards ethically sourced and lab-grown options in recent years.
  • Cubic Zirconia: CZ has seen fluctuating popularity based on fashion trends and economic conditions. Its lower price point makes it accessible to a wider audience, especially during times of economic downturn. Fashion trends that favor bold, statement jewelry often see a rise in the use of CZ, allowing for larger, more elaborate designs at an affordable cost.

Price and Value

  • Diamonds: Diamonds are significantly more valuable than CZ, reflecting their natural rarity, durability, and desirability. When buying a diamond, it is important to get a certified appraisal to confirm its authenticity and value.
  • Cubic Zirconia: CZ is much more affordable and is often used as a diamond simulant in costume jewelry. Its lower price reflects its synthetic origin and differences in durability and brilliance.

Conclusion

Distinguishing cubic zirconia from diamond involves a combination of visual inspection, understanding physical properties, and using professional testing methods. At Plateau Jewelers, we offer expert guidance and tools to help you identify the true nature of your gemstones. Whether you’re buying, selling, or simply curious, our team is here to assist you in making informed decisions.

For more information or to schedule a consultation, visit Plateau Jewelers. Let us help you explore our collection and ensure you find the perfect piece that meets your standards of beauty and authenticity.

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