What is depth of field in gemology?

• A. The distance that's clear and sharp above and below the focus point
• B. The thickness of the girdle
• C. The distance across the table
• D. The angle of the pavilion

Answer: (A)

Depth of field in gemology is the range of distance from the lens or focusing point within which the image stays clear and sharp. It’s the portion above and below the focus point that remains in acceptable focus, so you can see a feature or inclusion as you move through different depths of the stone. This matters when inspecting for inclusions or symmetry, because a stone can contain details at various depths that you’ll only see clearly if they fall within this focus range. The other options describe physical dimensions or angles of the gem (girdle thickness, table width, pavilion angle) and do not define how much of the stone’s depth remains in focus.