Traditionally, nail polish started in clear, red, pink, purple, and black. Nail polish can be found in a diverse variety of colors and shades. Beyond solid colors, nail polish has also developed an array of other designs, such as crackled, glitter, flake, speckled, iridescent, and holographic. Rhinestones or other decorative art are also often applied to nail polish. Some polish is advertised to induce nail growth, make nails stronger, prevent nails from breaking, cracking/ splitting, and to even stop nail biting.