Which tool is commonly used to file the natural nail during a manicure?

The emery board is the tool commonly used to file the natural nail during a manicure. It features a rough surface that effectively shapes and smooths the edges of the nails. The emery board is versatile and can be used on both natural nails and artificial nails, making it a staple in nail care. Additionally, its ease of use allows for precise filing without the risk of damaging the nail structure.

Buffers, on the other hand, are designed for smoothing the surface of the nail and adding shine, rather than filing down the nail length. Nail clippers are primarily used for cutting the nails rather than filing them, and cuticle pushers are tools used to push back the cuticles and do not serve the purpose of shaping or filing the nail itself. Therefore, the emery board stands out as the appropriate tool for filing during a manicure.