Lab-Grown Diamonds vs. Cubic Zirconias

by Tom Thornbridge

When it comes to choosing an alternative to natural diamonds, two popular options often come to mind: lab-grown diamonds and cubic zirconia (CZ). Both have their unique qualities and appeal, making them suitable for different types of jewelry and occasions. This article will explore the differences between lab-grown diamonds and cubic zirconia, helping you make an informed decision on which option is best for your needs.


In summary, let’s quickly compare lab-grown diamonds and cubic zirconia:

  • Luxury and Use: Lab-grown diamonds carry a luxury aspect, making them ideal for engagement rings and fine jewelry. In contrast, CZ rings are much cheaper and commonly used for casual jewelry.
  • Cost: A 1.00 carat lab-grown diamond typically costs between $500 and $2,000, depending on its characteristics. Cubic zirconia, on the other hand, is significantly cheaper, ranging from $5 to $50.
  • Appearance: To the untrained eye, CZs look very similar to diamonds, making them a great option for casual, everyday use.
  • Availability: Both lab-grown diamonds and CZs come in various colors and qualities.
  • Identification: A jeweler can distinguish between natural diamonds, lab-grown diamonds, and cubic zirconia. Lab-grown diamonds will test as real diamonds, while CZs will not.
  • Composition: Cubic zirconia is considered a synthetic diamond simulant, whereas a lab-created diamond is regarded as a real diamond due to its pure carbon composition.

Both lab-grown diamonds and cubic zirconia have their place in the world of jewelry. Lab-grown diamonds offer a luxurious, genuine diamond alternative, perfect for significant pieces like engagement rings. Cubic zirconia, with its affordability and similar appearance to diamonds, is ideal for everyday, casual jewelry.

For more detailed information and to find the best lab-grown diamonds, read my reviews on the top retailers:

What is a Lab-Grown Diamond?

Lab-grown diamonds, also known as synthetic or cultured diamonds, are created in a controlled laboratory environment using advanced technological processes. These diamonds have the same physical, chemical, and optical properties as natural diamonds, making them indistinguishable from mined diamonds to the naked eye.

1.00 ct D VVS1 Round Cut Precision Lab Grown Diamond from Whiteflash

There are two primary methods for creating lab-grown diamonds:

1. Chemical Vapor Deposition (CVD): CVD involves placing a diamond seed in a chamber filled with carbon-rich gas. The gas is then ionized, causing carbon atoms to deposit onto the seed, gradually forming a diamond. This method allows for precise control over the diamond’s characteristics, resulting in high-quality stones.

2. High Pressure High Temperature (HPHT): HPHT mimics the natural diamond formation process by subjecting carbon to extreme pressure and temperature. The carbon crystallizes to form a diamond. This method can produce gem-quality diamonds that are virtually identical to natural ones.

2.28 Ct. Fancy Vivid Yellow Round Lab Grown Diamond from Brilliant Earth

Lab-grown diamonds are an excellent choice for those seeking the luxury and durability of a diamond at a more affordable price. They are particularly popular for engagement rings and fine jewelry due to their identical properties to mined diamonds.

What is Cubic Zirconia (CZ)?

Cubic zirconia (CZ) is a synthetic gemstone that is often used as an affordable alternative to diamonds. It is made from zirconium dioxide (ZrO2), a crystalline form of zirconium. The process of creating CZ involves heating zirconium oxide powder to temperatures over 1000 °C (1832 °F) in a furnace, resulting in a bright, sparkling gemstone.

A product listing for an Asscher Cut Cubic Zirconia loose stone of 5A quality on The image shows a high-quality Asscher cut cubic zirconia stone with detailed faceting and sparkle. The price is $12.39 USD.

Asscher Cut Cubic Zirconia loose stone of 5A quality available on for $12.39 USD.

Key Characteristics of Cubic Zirconia:

  • Composition: CZ is composed of zirconium dioxide, unlike lab-grown diamonds which are made of pure carbon.
  • Appearance: To the untrained eye, CZ can appear very similar to a diamond due to its high sparkle and clarity. However, CZ has a lower refractive index, meaning it doesn’t exhibit the same level of brilliance and fire as a diamond.
  • Usage: CZ is popular for casual jewelry and fashion pieces due to its affordability. It is an excellent choice for those looking to enjoy the aesthetic of a diamond without the associated cost.
  • Market Value: Unlike lab-grown diamonds, CZ holds very little market value and is considered a diamond simulant rather than a real diamond.

While cubic zirconia is not considered a real diamond, it remains a popular choice for daily wear and budget-friendly jewelry. Its ability to mimic the look of a diamond makes it ideal for those entering the jewelry world without a significant investment.

Which One Will Pass a Diamond Test?

When it comes to passing a diamond test, lab-grown diamonds are virtually indistinguishable from natural diamonds. Since they share the same chemical and physical characteristics, lab-grown diamonds will test as real diamonds. However, distinguishing between natural and lab-grown diamonds requires specialized equipment available only at gemological labs.

On the other hand, cubic zirconia (CZ) will never test as a real diamond. Due to its different thermal conductivity levels, a standard diamond tester will easily identify CZ as a diamond simulant, not a genuine diamond.

Lab-Grown Diamonds vs. Cubic Zirconia

When comparing lab-grown diamonds to cubic zirconia (CZ), several key differences emerge that can influence your choice depending on your needs and preferences. Let’s delve into these distinctions:

Price: Lab-grown diamonds are significantly more affordable than natural diamonds, typically costing 60-80% less. A 1.00 carat lab-grown diamond generally sells for mid to high three-digit prices, making them a cost-effective option for those seeking the luxury of a diamond without the hefty price tag. In stark contrast, cubic zirconia is extremely inexpensive. A 1.00 carat CZ can be found for as little as $15-$30, reflecting its status as a budget-friendly option for casual jewelry rather than a luxury item.

Durability: Lab-grown diamonds, sharing the same physical and chemical properties as natural diamonds, are incredibly durable with a hardness of 10 on the Mohs scale. This makes them the hardest known mineral, ideal for daily wear and fine jewelry. Cubic zirconia, while relatively durable with a Mohs hardness of 8-8.5, does not match the resilience of diamonds. Though suitable for casual wear, CZ is more prone to scratching and wear over time.

Appearance: Lab-grown diamonds exhibit exceptional brilliance, fire, and sparkle, especially when cut to high standards. They are available in various colors, including yellow, red, pink, and blue, though colorless options are often the most sought after. Cubic zirconia, on the other hand, has a more limited brilliance and fire compared to diamonds. However, CZs come in a broader range of colors, such as emerald green, black, violet, and more, offering versatile options for fashion jewelry.

Quality Grade: Lab-grown diamonds are graded similarly to natural diamonds using the 4Cs: carat, color, clarity, and cut. It’s crucial to purchase lab-grown diamonds with certification from reputable labs like IGI or GIA to ensure quality. Cubic zirconia uses a different grading system, starting from “AAAAA” for the highest quality to A/AB for the lowest. High-quality CZs will appear clear and vibrant, while lower-quality stones may look dull and cloudy.

My Personal Recommendation

In my opinion, lab-grown diamonds are the superior choice for fine jewelry, including engagement rings and significant pieces. They offer more brilliance, fire, and sparkle compared to cubic zirconia (CZ). Additionally, lab-grown diamonds are just as hard and durable as mined diamonds, making them perfect for everyday wear. The significant cost savings—up to 80% less than natural diamonds—make lab-grown diamonds an excellent value without compromising on quality.

However, if you are looking for fashion jewelry or if your budget is tight, cubic zirconia can be a great option. CZs offer a diamond-like appearance at a fraction of the cost, making them ideal for casual and fashion jewelry. They allow you to enjoy the look of diamonds without the financial investment, making them perfect for trendy or temporary pieces.


When choosing between lab-grown diamonds and cubic zirconia, consider your needs and budget. For those seeking luxury, durability, and exceptional sparkle, lab-grown diamonds are the best choice. They provide the same benefits as natural diamonds at a more affordable price. For fashion jewelry or budget-friendly options, cubic zirconia offers an attractive alternative that mimics the appearance of diamonds without the high cost.

For the best lab-grown diamonds, I recommend checking out these trusted retailers:

Explore these options to find the perfect lab-grown diamond for your needs.

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