Coatings for photoluminescent materials

A coated photoluminescent material, said coating being a multifunctional coating comprising:

• a photoluminescent material having a surface;
• and
• at least two oxides, the two oxides including:
• a primer material having a primer thickness on the surface of said photoluminescent material, said primer thickness functioning to at least inhibit a leaching of a component of said photoluminescent material into said coating;
• an outermost, sealant material having a sealant thickness that functions to inhibit or prevent oxygen and moisture from diffusing through said coating and into said photoluminescent material;
• and
• a gradient-interface thickness between said primer thickness and said outermost, sealant thickness, said gradient-interface thickness having a composition that changes continuously through the thickness from being predominantly a primer material composition to a predominantly sealant material composition;
• wherein said at least two oxides are selected from the group consisting of metal oxides and semiconductor oxides.