The structure of pigments is assigned based on thermogravimetric and differential thermogravimetric analysis (TG-DTGA),
X-ray diffractions (XRD), and UV–vis spectroscopy. Also, diffuse reflectance spectroscopy (DRS) using CIE L*a*b* parameter measurement
method, infrared spectroscopy (IR) and transmission electron microscopy (TEM) is used.