During the process of laser engraving, Depending on the exposure time and product the color changes and creates a contrast, Or the material evaporates or burns. 

The resulting laser engraving is permanent and very resistant to abrasion, Laser engraving is generally considered permanent and can last as long as the material itself, particularly on materials like metal, glass, and stone, where the engraving can endure a lifetime; however, on softer materials like wood or leather, longevity depends on usage and exposure to elements.