Watch the world's greatest cities rise and fall over the past 4,000 years. 1  These are the 25 most high-tech cities in the world. 2  Scientists have cracked Rome's secret to waterproof concrete. 3  These mega-projects will transform the world's greatest cities by 2030. 4  The inequality we're not talking about: house prices.
When it comes to makeup, color is the name of the game. Minerals provide the color to eyes, cheeks, lips, and nails. Iron oxide, one of the most important color minerals, was used by Cleopatra in the form of red ochre as rouge. Today, iron oxides give red, orange, yellow, brown, and black tones to makeup. Chrome oxides are used for greens; manganese violet for purple; ground lapis lazuli may be added to makeup for blue.
Quick Answer. The main cause of a purple tinge in fingernails is low oxygen levels in the blood. This can be caused by poor circulation, as well as habits that inhibit oxygen absorption such as smoking. A single fingernail may also become purple if it has been injured, indicating a bruise underneath the nail.