The key factor is whether the colors are put up together in a retail set — for example, a boxed assortment of watercolor pans or a multi-tube acrylic kit. Individual tubes, jars, or bottles sold separately fall under 321390 even if they are the same product, because they are not presented as a set.

Many tariff lines covering artist colors originating in China are subject to Section 301 measures. Importers should verify the specific 10-digit HTS line and the applicable Section 301 list before entry, as coverage and rates vary by line.