While the causes of the discoloration can differ depending on the quality of the jewelry and the specific chemical makeup of a person's body, it is relatively easy to get rid of a dark ring caused by jewelry. Sometimes inexpensive costume jewelry can leave a dark ring simply because the combination of cheap manufacturing, sweat and cosmetics causes the necklace's coloring to be transferred onto the body. Depending on the reason for the dark ring left by a particular necklace, some cleaning agents may work better than others.

Choose a cleaning agent that you know your body does not have any adverse reactions to. To prevent any allergic reactions, choose a mild cleansing agent such as vegetable oil or dish soap. Otherwise you may want to use a harsher agent like lemon juice.

Clean your skin with a regular facial cleanser and water. If the dark ring persists, gently dip a washcloth into the cleaning agent you have chosen. Do not saturate the cloth, as it is better to remove the ring in smaller sections that to douse it with cleaning product and risk irritating the skin. It is possible to mix any of the cleaning agents listed above if one alone does not seem to work. Avoid using skin scrubs or scrubbing excessively hard with a washcloth, as a scrubbing action in conjunction with the cleaning agent may also cause redness and irritation. Lightly dab at the area around the neck where the necklace has left a dark ring.

Pat the area dry with a soft hand towel and examine the neck for any remnants of the dark ring. If the ring is still there after you've tried multiple cleaning agents, this may be an indication that you have a skin allergy to the type of metal used in the necklace. The dark ring will eventually fade, but it is best to consult a physician.

Apply a light lotion to the area after drying it completely, to ensure that the area affected does not become dry or irritated after the cleansing. Wash the necklace or piece of jewelry in question with jewelry cleaner or tarnish remover.