Stretch marks are caused by when the skin could of been overstretched, they tend to be scars that are pretty close to purple or red in color and appear in areas. The Stretch Mark is there because the middle layer of the skin called the Dermis layer was stretched to the point that the connective fibers snapped. Stretch Marks can go through a transition of colors but are usually more pronounced during the early stages of the Mark being developed. Stretch Marks tend to lose their color over time and will eventually end up in a sort of clear to white shimmering mark. These causes of Stretch Marks usually develop around the stomach, hips, breasts, buttocks, and thighs. A large percentage of women will develop stretch marks during their pregnancy, as this is typical to see during your third trimester. The reason for this is because at that time the stomach is bulging from the waist for the growing uterus. The other reason that is a cause for stretch marks are rapid weight gain. Best Stretch Mark Removal has a list of great products that can try to prevent these Stretch Marks during pregnancy and rapid weight gains, or even slowly reduce the appearance of the Stretch Marks.