What is a key characteristic of latent prints etched in metal?

Latent prints etched in metal are often unique due to the nature of the surface and how the print interacts with it. When prints are found on such surfaces, they can often be quite faint and require careful handling to preserve their details. Therefore, it's crucial to photograph them exactly as they appear at the moment of discovery. This ensures that any interpretation or analysis made later can be based on an accurate representation of the print as it was found.

Photographing these prints is fundamental for documentation, as it captures the specifics of the ridge detail and any other characteristics, which may not be observable if the prints are developed using various chemicals or techniques. Photographing also helps to maintain the integrity of the evidence before any further processing that might alter or damage the print.

The other options discuss aspects that do not capture the nature of how handling and analysis of prints can be affected based on the surface type, leading to potential misunderstandings about the nature of latent prints in terms of reproduction, development, or comparison with prints found in plastic.