Natural Cosmetics Act This bill requires the Food and Drug Administration (FDA) to issue a final rule defining the terms natural and naturally derived ingredient with respect to cosmetics (including personal care products). It also prohibits the sale of a cosmetic that includes these terms on its packaging or labeling unless the cosmetic meets the definitions established under this bill. The FDA must issue the final rule within two years of this bill's enactment. When developing the definitions, the FDA must (1) consider how each ingredient in a cosmetic is processed; (2) consider any impurities that would adversely impact human health; and (3) base the definitions on relevant scientific data, including data on consumers' understanding of such terms when applied to cosmetics.