Final answer:
To smooth out the ridges on a nail plate, a nail buffer or nail file is used. It's essential to gently use these tools to prevent damage to the nail and surrounding skin.
Step-by-step explanation:
The implement used to smooth out the ridges on the nail plate is typically a nail buffer or nail file. These tools are designed to gently buff or file down the surface of the nail body, which is made up of densely packed dead keratinocytes, to create a smooth appearance. It's important to use these tools carefully to avoid damaging the nail bed and surrounding tissues like the nail cuticle and nail fold.