Humans can discriminate between hundreds of colors, which are clustered into a smaller number of color categories that can receive distinctive linguistic labels. Being color perception universal, languages differ in the set of basic color terms (BCTs) they have. Despite numerous prior studies, the exact number of BCTs in Mandarin (Sino-Tibetan, China) and Spanish (Indo-European, Spain) is still debated. Also, cross-linguistic differences can be expected with regards to how BCTs are used for referring to color, as well as concerning the naming strategies used for making reference more specific. For clarifying this, we recruited 21 speakers of Mainland Mandarin and 21 speakers of Castilian Spanish and assessed them in two related tasks: the list task, in which participants are asked to write down as many color names as they can recall; and the color naming task, in which they were asked to name color chips from the Munsell color chart that are presented randomly. Our results suggest that Mandarin has 9 BCTs, while Spanish has 12 BCTs. Additionally, we found that, in order to make color reference more exact, speakers of Mandarin use more modified terms and compounds, whereas speakers of Spanish rely more on monomorphemic non-basic terms. Finally, we observed that speakers of Mandarin use some colors (gray, blue and purple) less consistently, although the color space is partitioned similarly by these two languages. Our results reinforce the view that there are universal constraints on color naming, that are compatible with subtle cross-cultural differences in how colors are used.