The Different Ways Of Darkening Silver
Oxidized silver jewelry brings out the beautiful, fine engravings on a piece by creating contrasting patterns. Sometimes, this oxidation may be natural. In some cases, the beautiful warm, rich colors on the piece of jewelry are a sign of being lovingly worn by the owner. It can also point out a history or antique value, and actually even raise the value of a piece.
In fact, the darkening of the fine lines in sterling silver is so desirable that sometimes factories artificially produce the effect. If you have ever considered placing your silver in a dishwasher or fading out the dark lines, you would actually be reducing the value of your silver!
It is also important to keep in mind when purchasing silver that some sellers try to pass off tarnished silver (which is not desirable) as silver with a patina (which is desirable). When buying sterling silver jewelry online, you may come across terms like "sterling silver patina" or "niello". What do these terms mean? They have to do with different processes of darkening of silver. Here is a look at some of the most common processes.
What is Patina?
You have probably heard of the term patina in reference to antique jewelry or even furniture. A patina is something that can increase the value of the object. But what is patina exactly?
A patina is a desirable, warm, rich color that sterling silver (and other materials) develops over time with use. Just like stainless steel or silverplate, sterling silver from the factory is usually shiny bright. Fine scratches develop over the silver surface with time, which is normal. With slow patination over time, the scratches seem to merge together and create a soft, warm finish over the metal. In addition, slow oxidation of the exposed surfaces leads to darkening of fine lines, and this oxidation can raise the value of the silver, as in antique jewelry.
Sterling silver that has been worn regularly develops a mix of darkened areas and glow. Some people prefer this kind of look on their silver, but if you don't you can polish the piece (with a non-abrasive polishing cloth) to restore its original bright coloring.
What is Tarnish?
Often, you will find online silver jewelry sellers trying to pass off tarnish as a patina. Tarnish may look somewhat like patina - it is a blackening of the metal all over the surface. But it is formed through the corrosion of the metal surface and is really quite easy to distinguish from patina. Tarnishing is the result of pollution, and it is interesting to note that this is a recent phenomena. Silver did not tarnish before the Industrial Revolution!
Tarnish occurs when pollutants in the air, like oxygen in the presence of hydrogen sulfide or sulfur dioxide and humidity, react with the surface layers of silver. It often occurs as a dull black or grey film all over the silver. The tarnished layers prevent the lower layers from reacting with the atmosphere. But at the same time, they can also hide imperfections and defects in the piece. What is worse, the tarnish actually removes silver from the surface layers by converting it to compounds that cause the darkening.
Should You Remove Tarnish?
It depends. If you are using the silver for jewelry or silverware and don't like the darkening of the metal, you can go ahead and get some silver remover. This also applies if the piece you are holding has some collector's value and should not lose its appeal.
But if you are holding the silver for its investment value - weight value - then removing the tarnish will actually remove the silver and devalue your piece.
How to Prevent Tarnish
You can prevent your favorite silver jewelry from tarnishing by taking care not to leave it around in the bathroom and never wear it in the pool or shower. Moisture speeds up tarnishing, so you should also avoid contact with perfumes, hair spray, lotions and other chemicals as far as possible. Also, remember that rubber bands can release sulfur, which aids tarnishing, so never use rubber bands with your jewelry. When storing your jewelry, wipe it gently with a soft, dry cloth and keep it in an air-tight container.
What is Oxidation with Liver of Silver?
There is another process of deliberately oxidizing the surface of sterling silver to give it a darkened patina. This is done by using liver of silver, a compound called potassium sulfide that has been used for giving an antique finish to brass and silver. A solution of the compound in warm water is created by dissolving a solid piece in warm water and diluting it to the desired dilution. The silver piece is then dipped into the solution for a few seconds, removed and rinsed. The process is repeated until the craftsman gets the desired darkness he wants to achieve.
The piece may also be brushed with some soapy water after the final rinsing or sand-blasting it before dipping it in the liver of silver solution. A wonderful, rich blue-black or a shade of steel grey can be achieved on silver with these processes. The silver can then be polished for additional effect.
What is Niello?
You may also find silver jewelry with the Niello effect, and wonder what that is. Niello is the name given to a mixture of silver, copper and lead sulfides used to etch or engrave metal. It is a very old method and has been around since the Egyptians used it for decoration and made it popular across the rest of the world. Goldsmiths used the process in the 15th century for engraving high contrast designs, sculptures, jewelry and other metalwork. The craftsmen and jewelers from Kievan Rus, a Slavic culture that existed during the 9 to 11th centuries were known for their Niello technique.
These are the different techniques of darkening gold, and knowing about them can help you make better choices when buying silver. A warm patina is natural and something you may want on your jewelry. Don't but tarnished jewelry passed off as patina, at least not for the same price. If you want vivid, beautiful ornamentation in which the intricate designs stand out more strikingly, you may want to go for a Niello technique. Finally, if you love the look of lustrous black silver, you may want oxidized pieces.