Lesson 6 · Diamonds explained · 52 seconds
Lab-grown diamond vs cubic zirconia.
They can look alike at a glance, but they are different materials. One is diamond. The other is a simulant that imitates diamond's look. The lesson shows the one check that separates them.
What this lesson shows
Diamond is diamond. CZ is a different material.
A lab-grown diamond is diamond: carbon in the same crystal structure as a mined diamond, with essentially the same optical and physical properties. It is grown, not mined.
Cubic zirconia is zirconium oxide, a lab-made material. It imitates diamond's look at a glance, but it is a different material with different properties. On the Mohs scratch scale, diamond is a 10 and CZ is about 8.5.
Three quick takeaways
How to shop without getting fooled by a photo
- Read the exact stone named on the listing. "Lab-grown diamond" and "cubic zirconia" are different materials, not synonyms.
- If it is a diamond piece, check for a grading report (GIA, IGI, GCAL). Simulants are not graded on the diamond scale.
- Do not rely on a photo. Both can look brilliant in staged lighting.
The stones in the lesson are computed models used to compare properties. They are not grading-report images.
Read the transcript
Is a lab-grown diamond the same as CZ? No. They can look alike, but they're different materials. A lab-grown diamond is diamond: carbon, in the same crystal structure as a mined diamond, with essentially the same properties. It's grown, not mined. Cubic zirconia is a different material: lab-made zirconium oxide. It's a simulant. It imitates diamond's look, but it isn't diamond. On the Mohs scratch scale, diamond is a ten. CZ is about eight and a half. So don't rely on your eye or a photo. Check the listing for the exact stone, and the grading report if there is one. Save this before you shop for stones.
Sources
- FTC 16 CFR 23.12 and 23.25(b) (Guides for the Jewelry Industry): diamond is defined by composition and structure; lab-grown and simulated stones must carry a clear qualifier such as "laboratory-grown" or "cubic zirconia." law.cornell.edu/cfr/text/16/23.25
- GIA 4Cs, "Laboratory-grown diamonds": lab-grown diamonds share the same crystal structure as mined diamonds and have essentially the same chemical, physical and optical properties. 4cs.gia.edu
- GIA 4Cs, "What are simulated diamonds?": CZ is a different material (zirconium oxide); on the Mohs scratch scale, diamond is 10 and CZ is about 8.5. 4cs.gia.edu
Related lessons
See same carat, different look for how to compare two diamonds at the same carat, and total carat weight explained for how to read ct tw on listings.
Next step
Browse lab-grown diamond jewelry.
Every piece in our lab-grown collection names the exact stone and lists the carat weight. If you want a grading report, filter for pieces that include one.