Rubies are formed of a mineral called corundum, comprised of aluminum oxide. The red color is caused by traces of chromium. Corundum also forms sapphire in many colors, which generally come from ...

One feature of compounds made with transition metals is their intense colour. There are many examples in nature, including ...

Both rubies and emeralds are minerals, which is a type of rock with a consistent chemical composition and a highly ordered ...

Even the color of blood comes from the protein hemoglobin ... Rubies are mainly made up of the mineral corundum, which is composed of the elements aluminum and oxygen in a regular, repeating array.