Lab-Grown Diamond Buying Guide

What Is a Lab-Grown Diamond?

Lab-grown diamonds are diamonds created in a controlled laboratory environment using advanced technology. They have the same carbon composition, crystal structure, and optical properties as mined diamonds. Specialized testing is used to identify their growth origin.

How They Are Created

• HPHT (High Pressure High Temperature) — Recreates conditions deep within the Earth using temperatures of approximately 1,300–1,600°C and pressures of 5–6 GPa.
• CVD (Chemical Vapor Deposition) — Breaks down carbon-rich gas in a vacuum chamber and deposits carbon atoms onto a diamond seed, layer by layer.

Lab-Grown vs. Mined Diamonds

What to Check Before Buying a Diamond

1. Review the 4Cs

Cut, color, clarity, and carat weight are the four core quality factors. Read our 4Cs guide for a detailed explanation.

2. Verify the Grading Report

• GIA (Gemological Institute of America) — An internationally recognized grading laboratory known for rigorous standards.
• IGI (International Gemological Institute) — A widely used grading laboratory for lab-grown diamonds.
• Use the report number to verify the report directly on the issuing laboratory's website.

3. Consider Fluorescence

Fluorescence is the glow that can appear under ultraviolet light, graded from None to Very Strong. Strong fluorescence may affect appearance in some stones, so review it together with color and overall visual performance.

4. Review Proportions

Common reference ranges for a round brilliant diamond include:

• Table: 54–57%
• Depth: 61–62.5%
• Crown angle: 34–35°
• Pavilion angle: 40.6–41°

5. Choose a Shape

Round brilliant is the most familiar shape, while oval, cushion, emerald, princess, pear, and marquise cuts each have a distinctive character. At the same carat weight, elongated shapes such as oval and marquise can appear larger face-up than a round stone.