Rare-earth oxide additives that can offer tunable properties for optical and protective coatings and films. The crystals are highly uniform in size and shape, and are made from abundant and non-toxic rare earth elements. They have tunable optical and physical properties and can be deposited on any substrate via spray, spot or powder-coating to create unique optical signatures and block certain wavelengths of light. The use of different surface modifications enables easy dispersion and excellent stability in a variety of binders and deposition methods. These coatings are broadly applied for protection of metallic tools and structures, providing a corrosion-resistant barrier via release of ionic species. The rare-earth oxides can be used as non-toxic alternatives to chromate-based primers in corrosion-resistant applications. The proprietary methods developed for high purity anti-corrosion pigments can be readily scaled for large-volume production. Applications include infrared blocking, visibly transparent films for ID and transaction cards, as well as smart coatings for the paint and coating industry such as non-toxic corrosion inhibitors.