Importantly, TiO2 also has a very high refractive index (its ability to scatter light), even higher than diamond. This makes it an incredibly bright substance and an ideal material for aesthetic design use.

For those wishing to limit or avoid exposure to titanium dioxide in foods, there are some steps you can take. 

Particle size: optimum particle size to produce maximum opacity is 200–300 nm.

In 1970, Japanese scholars studied the phase diagram of iron oxide microcrystalline formation, which laid a theoretical foundation for the preparation method of iron oxide yellow crystal seed. According to the research results, iron yellow crystal seeds can be formed under acidic or alkaline conditions. Because iron yellow is a crystal structure, in order to crystallize into pigment particles, it must first form crystal nucleus and become crystal seed, and then the crystal nucleus grows into iron yellow. Otherwise, only thin and dim color paste can be obtained, which does not have pigment properties. Acid process can be divided into iron sheet process and drop addition process.