What is the effect of extremely thick or thin girdle thickness on a diamond's durability?

• A. It changes color grade
• B. It changes refractive index
• C. It affects light performance but not durability
• D. It increases the risk of chips or affects weight

Answer: (D)

Girdle thickness directly influences durability because the girdle is the edge-most part of the diamond that faces impact in wear and setting. If the girdle is extremely thin, it’s weak and prone to chipping or cracking from accidental knocks or during setting. If the girdle is very thick, you gain extra material, which increases the diamond’s overall carat weight; this added mass can affect how the stone behaves in a setting and under stress over time. Colors and refractive index aren’t determined by girdle thickness, and light performance isn’t the primary durability concern. So the risk to durability comes from thin girdles increasing chip risk and thick girdles increasing weight.