However, it can lighten and darken its skin to match its surroundings. His eyes are brown with flecks of gold that lighten and darken with his moods. The back is darker than the sides, which gradually lighten in color. In the story, humour is used to lighten up and contrast with the darker theme. To lighten up the mood she decides to announce the engagement. It is commonly used to lighten mixtures subtly while maintaining transparency. With continuity of use over time, tooth colour can lighten by one or two shades. I think myself they will lighten up the book. Efforts to lighten the skin date back to at least the 1500s in Asia. After two weeks, they lighten in colour, with black tones remaining only around the eyes. Semi-permanent hair color cannot lighten hair. He is overly formal, causing some of his comrades to wish he would lighten up. They are sometimes bleached during the production process to lighten the paper's coloration. A fuller is often used to lighten the blade. These touches serve to lighten an interaction.