Stretch Marks are stirpes that appear on our stomach, breasts, hips, thighs. These stripes or lines are not harmful, but they don't appear great to look at. They do not fade away over time. They can only disappear with the help of a few products and procedures. Skin can stretch. When skin stretches beyond its capacity, the normal production of collagen, a tissue in the skin gets disrupted and develops a mark called stretch marks. Collagen is protein tissue that is responsible for our skin elasticity. The color of stretch marks is slightly different from the skin and so we can differentiate it.