MesoGold is .9999 pure gold nanoparticles in colloid form, a TRUE colloidal gold, which means 100% gold nanoparticles, with no ionic content. Highest particle surface area. Highest bioavailability of any colloidal gold product, due to nanometer sized particles. Smallest gold nanoparticles, typically between 2-4 nm. Colloidal gold is an all natural mineral supplement. Made with the highest purity, sterile reagent grade deionized water. Colloidal gold does not require refrigeration after opening. Infinite shelf life. MesoGold is non toxic (per Material Data Safety Sheets). NOTE: high PPM (parts per million) does NOT necessarily mean high PSA or bioavailability. Colloidal gold concentration is 10 ppm minimum. Please see our web site "purestcolloids" or our company information here on for more technical information on colloidal gold and the pitfalls of some other products. It is very important to read and understand why our product is different then competing products. MesoGold is a registered trademark of Purest Colloids, Inc.