Knowing the parts of a diamond makes grading reports easier to read and shows why proportions matter so much.

The main parts

• Table: the large flat facet on top. Light enters here.
• Crown: the upper section, from the girdle up to the table.
• Girdle: the thin edge around the widest part, where the stone is held in the setting.
• Pavilion: the lower section that reflects light back up.
• Culet: the small point or facet at the very bottom.
• Facets: the flat polished surfaces that cover the stone.

Why proportions matter

Light travels in through the table, reflects inside the pavilion and returns through the crown. If the stone is cut too shallow or too deep, light leaks out the bottom or sides and the diamond looks dull.

What to check on a report

• Table and depth percentages.
• Girdle thickness: very thin edges chip more easily, very thick ones add weight you cannot see.
• Culet: a small or no culet is the norm.