Why are your jewelry get black? Why do earrings, rings, necklaces and bracelets oxidize? In this article we explain from a scientific point of view what happens to your jewels when they oxidize. If, on the other hand, you want to know how to eliminate oxide from your jewels, read here.
Some jewels, particularly those of silver, tend to oxidize and become black or with shades tending to green. It is the effect of oxidation. In some cases, jewelers take advantage of this change in metal and offer jewelery with partially blackened surfaces. But in this case it is an aesthetic choice. The problem, however, is when oxidation is not desired. Let’s consider this aspect from a scientific point of view to understand how oxidation occurs.
A metal oxidizes occurs when a chemical reaction occurs on its surface. Oxidation occurs because the electrons that make up the atoms of some metals (not all of them, we’ll talk about it later) move from the metal to the oxygen molecules. In essence, they divorce their spouse (the rest of the atom, that is, the central nucleus and the other electrons) and become engaged to another: oxygen. It is a process that in chemistry is called ionization. When they escape from the metal, the electrons that have divorced from their original nucleus to join the oxygen, create the oxidized surface. Basically, they are family breakers.
Why does oxidation occur?
That’s the best part. You can’t blame all the fugitive electrons. In families, the faults are not (almost) all of a single partner. In this case, the chemical process that leads to oxidation can be caused simply by contact with the air, and therefore with the oxygen it contains. Or oxidation can be caused by the metal exposed to water (even water contains oxygen) or to acidic substances that corrode it, for example, cosmetic creams or skin sweat. In short, oxidation occurs because the electrons of the metal are seduced by the irresistible call of oxygen: a true chemical betrayal.
Anti oxidation metals
Fortunately, not all jewelry oxidizes. As all women know, if they give you a gift or if you buy a gold jewel, you can rest assured: it will not blacken (except in rare cases, when it is alloyed with metals that oxidize). In addition to gold, there are metals that are not by chance called noble, which do not blacken, such as platinum, ruthenium, rhodium, palladium. Other metals, which however are not classified as noble, resist oxidation and are used in jewelry, such as titanium and aluminum. Finally, there are also metals invented by man, that is alloys of different materials, which are not sensitive to oxygen, such as stainless steel and brass.
