Silver turns black when kept in the air because it reacts with sulphur compounds such as hydrogen sulphide (H2S) present in air. The phenomenon is called corrosion and, for silver in particularly, is called tarnishing. The black substance formed is silver sulphide.
While jewelry that's made of pure silver or gold doesn't tarnish, cheaper alloys in fake jewelry will start to change colors and oxidize over time. If you have fake jewelry that's lost its original shine or color, there are easy ways that you can clean and polish it at home.
Blackened or oxidized silver is genuine sterling silver, but its outer surface has been purposely darkened via a chemical process. This essentially speeds up the natural tarnishing process, creating an attractive dark patina, which consists of a layer of silver sulfide on the exterior of the metal.
It is a natural reaction for your jewelry to tarnish over time. The blackened color of this metal indicates, precisely, that our jewelry is made of 925 Sterling Silver. 925 Sterling Silver darkens due to daily use, as well as for other reasons.
Quickly restore your jewelry or tableware with vinegar, water and baking soda. This cleaning agent is a great option for many things, including your tarnished silver. Mix 1/2 cup of white vinegar with 2 tablespoons of baking soda in a bowl of lukewarm water. Let the silver soak for two to three hours.
Mix two parts baking soda with one part water to make a paste, then gently rub the mixture onto the jewelry. Let the paste dry completely to remove the tarnish.
The Magnet Test
"Silver is not noticeably magnetic, and exhibits only weak magnetic effects unlike iron, nickel, cobalt, and the like," says Martin. "If your magnet sticks strongly to the piece, it has a ferromagnetic core and is not silver." Fake silver or silver-plated items are generally made of other metals.
Silver becomes black because of hydrogen sulfide (sulfur), a substance that occurs in the air. When silver comes into contact with it, a chemical reaction takes place and a black layer is formed. Silver oxidizes faster in places with a lot of light and high humidity.
If your sterling silver tarnishes, that's actually a sign that it's real. Fake silver will lose its shine over time, and underneath can be any number of ugly cheap base metals that may turn your skin green.
When fake silver is exposed to heat and other chemicals it turns into a bright copper like color with a tinge of green and orange – this means it exposes the based metal indicating that the silver was just a covering top layer.
If you do not see the sterling marking, the item is probably silver plated. Check the colouring of the item carefully; genuine silver is generally less shiny and colder in tone than silverplate. If you see places where the silver appears to be flaking off or turning green, the item is silver plated.
Sterling silver can begin to tarnish in anywhere from 2 months to 3 years, but don't let that worry you. Tarnish is no big deal and there are simple ways to clean and prevent it.
Look for the 925 marking.Genuine sterling silver jewelry will be marked with these three numbers or STERLING or STER. Hold a magnet to the silver. If the magnet sticks, your jewelry is not real sterling silver. Smell the sterling silver.If it smells strongly metallic, then your jewelry is not real sterling silver.
The tarnish on Sterling Silver consists of silver sulfide, a compound produced by pure silver reacting with sulfur, and copper sulfide, a compound produced by copper reacting with sulfur. The copper content in Sterling Silver is what makes it tarnish much faster and more readily than pure silver.
Sterling silver is a beautiful precious metal that is a favorite for many. However, without proper care, sterling silver can tarnish over time. Silver in its purest form does not tarnish. But pure silver is very brittle and can't be used for jewelry alone.
Pure silver, as you might have guessed, is made up of almost 100% silver. Because of this, it is very soft and pliable...not ideal for handmade jewelry like ours. Sterling silver, however, is composed of 92.5% pure silver and 7.5% other metals, like copper, nickel, or zinc.
Sterling silver tarnishes when exposed to salty air, chlorine, sulfur, humidity, perspiration, cosmetics, household bleach and other strong chemicals.
If you have to deal with stubborn built-up tarnish on your silver jewellery prepare a thick paste from baking soda and lukewarm water. Apply it onto the tarnished spots with a damp cloth. Leave it for 2-3 minutes then gently rub with soft cloth. Don't rub too hard to avoid scratching the surface.
Those stains are called fire stains or firescales. They do happen a lot when using sterling silver less with argentium and fine silver. you can remove them by repeatedly heating metal and pickling or polishing properly. Basically it's oxides on the surface of metal.
The jeweler will most likely conduct a simple and quick acid test that involves using a special solution. In this test, they place a drop of acid on the piece. If the color of the acid remains the same, you have a true silver piece.
Silver is not magnetic, not even with the strongest magnet. However, silver is diamagnetic. If you hold a silver coin at 45 degrees a suitable magnet will slide down it slowly. This is because the moving magnet sets up an 'electrical field'* that slows its fall.
The easiest way to tell if sterling silver is real is by finding the imprint on your piece. Rings, necklaces, and bracelets made of sterling silver will have a “925” stamp somewhere. On rings, the stamp is usually on the inside band. Bracelets and necklaces will often have them on the clasp or on a seperate charm.
When silver tarnishes, it's a surface discolouration caused by the interaction of oxygen (air) with the silver. As the British Assay Office explains it, “silver naturally interacts with oxygen and sulphur-bearing pollutants to create silver sulphide, resulting in a visible discoloration of the metal's surface.