Lab-Grown Diamond Buying Guide: vs Mined, the 4Cs and IGI Certificates
What is a lab-grown diamond?
A lab-grown diamond is grown in a laboratory by recreating the conditions in which diamonds form naturally. It is made of carbon with the same crystal structure as a mined diamond. It is not a simulant like cubic zirconia or moissanite. It is a real diamond that simply formed above ground.
There are two main growing methods:
- HPHT (High Pressure, High Temperature): recreates the heat and pressure deep in the earth so carbon crystallizes around a diamond seed.
- CVD (Chemical Vapor Deposition): carbon-rich gas is broken down in a vacuum chamber, and carbon atoms build up layer by layer on a diamond seed.
Lab-grown vs mined diamonds
| Lab-grown | Mined | |
|---|---|---|
| Composition | Carbon, cubic crystal | Carbon, cubic crystal |
| Hardness & sparkle | Identical | Identical |
| Can you tell by eye? | No, only with specialist lab equipment | |
| Price | Significantly lower | Higher |
| Certificate wording | States "laboratory-grown" | States "natural" |
A trustworthy jeweler will always disclose that a diamond is lab-grown. Check that both the certificate and the product description say so.
Understanding the 4Cs
- Carat: the diamond's weight. 1 carat = 0.2 grams. Because lab-grown diamonds cost less, a larger carat is often within reach.
- Color: graded from D (colorless) down the alphabet. D to F are colorless. G to H look white to most eyes and offer great value.
- Clarity: from FL (flawless) to I (included). VS grades and above usually look clean to the naked eye.
- Cut: the most important C for sparkle. For round diamonds, choose Excellent or Ideal.
On a budget? Prioritize cut first, then balance color and clarity.
How to verify an IGI certificate
IGI (International Gemological Institute) is one of the most widely used grading labs for lab-grown diamonds. To check a report:
- Find the report number on your certificate.
- Enter it in the report verification tool on IGI's official website, and compare the carat, color, clarity and measurements.
- Look at the diamond's girdle under a loupe. The report number is laser-inscribed there and should match your certificate.