National Museum of Natural History:

How are there diamonds of different colors?

by Autumn Brown

This image was obtained from the Smithsonian Institution.

At the Natural History Museum I saw a shiny, yellow diamond and I suddenly thought to myself why are diamonds different colors? Each one of the diamonds were a different color but had the same chemical formula. Some looked smooth and some looked rocky because each were mixed with different elements and molecules that help to create the uniqueness of each diamond.

Diamonds that are clear are made up of just carbon atoms, each of which has four valence electrons. Pure carbon is colorless. Diamonds that are yellow or a little bit of yellow are made up of carbon and a few nitrogen atoms, each containing five valence electrons. Diamonds with blue are made up of carbon and a few boron atoms, each containing three valence electrons. Diamonds get their different colors because of a defect in their structure related to impurities.

The reason why diamonds are different colors is because the nitrogen and boron are really almost the size of carbon. We know they are similar sizes because of the atomic number. Based on the periodic table below, you can see that the element nitrogen has one more proton and the element boron has one less than can fit in the carbon spot. Although the structure of the diamond does not change significantly, it does affect the color of different diamonds.

Based on my research I learned is that nitrogen and boron are the only two elements that change the color of diamonds. Also nitrogen makes a yellow color and boron makes a blue color and diamonds come from inside the earth and they are brought to earth by volcanoes and and diamonds made up of pure carbon!! So next time you see a different color diamond remember how did they got there clear, yellow, or blue color!