Here is my review: I had researched vitamin c serum for a couple of weeks to get the best of the best. I do not buy any products ( skin care, supplements, food etc.) unless it is independently third party tested & certified or certified organic. I picked kakadu plum vit c serum because it was echo (and other certificates) certified organic. I chose ascorbic glucoside vit c derivative for my vitamin c serum because, (although L ascorbic acid is the most potent form of vit c it oxidizes once air & water, or high heat hits it) Ascorbic glucoside is stable, and once it is on skin it converts to the powerful L ascorbic acid. Kora Organics was the best option out there. I also liked that the vit c is potent as it is the second ingredient listed in the ingredients list. That said, I unfortunately had to retrun this product due to the fact that it was mailed in extremely hot weather, and the product arrived alarming hot to the touch--which will ozidize all vit c and compromise the effecacy of vitamin c. All suppliers who mail any form of vitamin c would do well to use insulated packaging to protect it from the environment. Sincerely, Rhonda Monette