Iodine and gold / Йод и золото

I took 3 pieces of porcelain with gilding (in the form of a strip). Next, I prepared a solution: 10 ml of alcohol, 3 ml of water and a few drops of a drugstore solution of iodine - until brown, but that the solution remained clear. Of course, you can use just 5% iodine tincture, but it is opaque: you will not see how gold reacts with iodine under a layer of solution. In the first minutes of visual changes was not noticeable. Signs of dissolution of the gilding appeared after 10 minutes, and after 15 minutes almost complete dissolution occurred. From the golden strip there was only a brown ornament, which, as it turned out, was not made from gold. http://chemistry-chemists.com/N3_2017/ChemistryAndChemists_3_2017-P1-4.html#1111