The exploitation of cobalt mines for the use of its blue colorant in vitreous materials dates back to the second millennium BCE in Egypt and Iran. For this reason, cobalt mines in Iran hold significant value for studying the blue color of glazed ceramics. Evidence suggests that these Iranian cobalt mines were also important for Chinese potters. In this research, portable X-ray fluorescence analysis (p-XRF) was conducted on Mina’i ware, Lajvardina tiles, and blue and white ceramics from both Iran and China. The results further corroborate what scholars have previously suggested, revealing that during the Ming Dynasty (1365-1644 CE), locally sourced cobalt with a distinctive high manganese content was used in China. However, the cobalt used for the blue glazes in Iran dating from the 12th to 17th centuries CE was determined to have been obtained from at least two different mines. One of the key mines is likely Qamsar in Kashan, which has been mentioned in Persian texts regarding its cobalt. The second mine proposed in this research is the Takht-e Soleyman mine, which has a chemical composition aligns with that of the blue glazes predating the Ming dynasty in China. Additionally, its name corresponds to “Soleymani stone” in Persian texts and “Su-ma-li-qin” in old Chinese texts. Notably, the Takht-e Soleyman cobalt mine is located along the main Silk Road, making its trade with China more straightforward than that of other Iranian cobalt mines. This study suggests, for the first time, that the Takht-e Soleyman mine should be considered a potential source of traded cobalt in China and played a role in the initial introduction of Chinese potters to Iranian cobalt. Although p-XRF is a surface analysis tool with limitations in accurately determining differences in cobalt sources, this study provides new insights into cobalt trade and the interaction between Iranian and Chinese potters.