Rubies and emeralds have the colors they do because, like many substances, they absorb some colors of light. Most visible light, like sunlight, is composed of all the colors of the rainbow: red, ...

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

One feature of compounds made with transition metals is their intense colour. There are many examples in nature, including gemstones and paint pigments. Even the colour of blood comes from the protein ...

Researchers have proposed using polymer membranes modified with copper, zinc, and chromium metal ions for water purification. These polymers were used for the first time in water purification via ...