The crown angle is the angle that’s formed where the bezel facets meet the girdle plane. It’s related to crown height: The higher the crown, the greater the crown angle. Most diamonds have crown angles between 25° and 35°. Diamonds with crown angles shallower than 25° can be quite bright, but they are more susceptible to damage than stones with higher crowns.
Diamonds with shallow crowns should be set in mountings that protect the girdle area, like bezel settings, which surround the stone with a rim of precious metal. Shallow diamonds are better suited for use in jewelry where they’re less vulnerable to damage, like earrings and pendants.
Stones cut from shallow rough are a challenge for the cutter who tries to get the largest girdle diameter and the highest possible weight retention. As a result, they’re usually cut with shallow crowns and pavilions. They also tend to have larger table percentages and thin girdles.