Red and green over-glaze decoration on Chinese porcelains from the Song-Jin periods is critical to the development for Chinese ceramics. To characterize the identity, crystal size, and band gap width of the red colorant, red and green porcelain shards from the Linshui kiln produced in the Jin dynasty (1115–1234 ad) are investigated using Raman spectroscopy, X-ray diffractometry, and diffuse reflectance measurements. The colorant is shown to comprise hematite crystallites with the average diameter around 30 nm, and its crystal lattice is distorted as the result of the low firing of the decoration. The use of crystal size estimations coupled with band gap width calculations are believed to be employed for the first time on the study of Chinese archeological artifacts. Copyright © 2014 John Wiley & Sons, Ltd.