This product is not e-coated, or covered with an anti-tarnish Polish. You can thus blacken as and time, it is inevitable. It is impossible to predict time that a silver jewelry will be tarnish because it depends on many items, including the acidity of the skin of the person who wears.
925 sterling silver is extremely sensitive to moisture, avoid submerging jewelry in silver. If he gets wet accidentally, he must dry carefully.
To maintain your silver jewelry, it is not required to use commercial cleaners, inexpensive and natural products can be used. Part lemon and gives excellent results: dip a brush in lemon juice and rub the jewel in silver. Ash and baking soda can also be used.