Products using gold and silver nanoparticles and ions to absorb visible and UV light

A method of diffusing one or more of gold nanoparticles, silver nanoparticles, gold ions, and silver ions, into a solid transparent material, the material being a plastic, causing it to absorb at least some wavelengths of visible light, UV light, or both, the method comprising:

• (a) providing a first volume of organic solvent with one or more of gold nanoparticles, silver nanoparticles, gold ions and silver ions, blocked with one or more amine or thiol ligands, suspended in the organic solvent;
• (b) adding a quantity of the first volume of organic solvent to a volume of water and immersing the transparent material in the volume of water with the organic solvent added to it, or adding a quantity of the first volume of organic solvent to a volume of water with the transparent material immersed in it, such that there are a total of at least 3×10−9 moles of gold and/or silver as ions and/or nanoparticles added per liter of water;
• and
• (c) heating the volume of water to at least 50 degrees C. with the added organic solvent and the transparent material for a period of time of at least 5 minutes to cause the one or more of gold nanoparticles, silver nanoparticles, gold ions and silver ions to diffuse into the transparent material to cause the transparent material to absorb light at at least some wavelengths of visible light, UV light, or both.