This study uses 238 species of shellfish resources from the Dongtou Archipelago as samples, focusing on the provincial intangible cultural heritage craft of Dongtou shell carving paintings in Zhejiang Province. It examines their color characteristics and reveals the influence of the cultural integration of Minnan and Dong'ou on their style. The paper centers on the color expression of traditional shell carving paintings and analyzes the mechanism of their transformation from natural materials into an artistic language from the dimensions of "resources—style—texture." That is, regional resources provide a natural color system, artisans' color choices create a correspondence between subjects and shell colors, and the combination of natural texture and color gives the works a three-dimensional visual texture. On this basis, the paper outlines the logic and techniques of color application in shell carving, such as color matching, blending with patterns, and techniques for three-dimensional color shaping. Finally, it proposes three major insights for contemporary design: promoting green design, expanding visual expression, and enhancing the cultural attributes of products. This study fills a gap in the aesthetics of shell carving color and provides a reference for natural material color systems in the inheritance of intangible cultural heritage and contemporary design.