Editing Gemstone (section)

==Colors==
[[File: Aurora Pyramid of Hope.jpg|thumb|Nearly 300 variations of diamond color exhibited at [[Aurora Pyramid of Hope|the Aurora display]] at the Natural History Museum in London]]
[[File:Semiprecious stones in a piece of jewellery.jpeg|thumb|A variety of semiprecious stones in a piece of jewellery]]
The color of any material is due to the nature of light itself. Daylight, often called white light, is all of the colors of the spectrum combined. When light strikes a material, most of the light is absorbed while a smaller amount of a particular frequency or wavelength is reflected. The part that is reflected reaches the eye as the perceived color.<ref>{{Cite web |title=Seeing Color |url=https://www.amnh.org/explore/ology/brain/seeing-color#:~:text=Light%20travels%20into%20the%20eye,Cone%20cells%20help%20detect%20colors.}}</ref> A ruby appears red because it absorbs all other colors of white light while reflecting red.

A material which is mostly the same can exhibit different colors. For example, ruby and sapphire have the same primary chemical composition (both are [[corundum]])<ref>{{Cite web |title=Ruby and Sapphire: Gems of the Mineral Corundum |url=https://geology.com/gemstones/ruby-and-sapphire/ |access-date=2024-03-01 |website=geology.com}}</ref> but exhibit different colors because of impurities which absorb and reflect different wavelengths of light depending on their individual compositions. Even the same named gemstone can occur in many different colors: sapphires show different shades of blue and pink and "fancy sapphires" exhibit a whole range of other colors from yellow to orange-pink, the latter called "[[Padparadscha|padparadscha sapphire]]".<ref>{{Cite news|url=https://www.thenaturalsapphirecompany.com/blog/padparadscha-sapphires-a-buying-guide|title=Padparadscha Sapphires: 10 Tips On Judging The Rare Gem|date=2015-04-06|work=The Natural Sapphire Company Blog|access-date=2018-01-19|language=en-US|archive-date=January 19, 2018|archive-url=https://web.archive.org/web/20180119235335/https://www.thenaturalsapphirecompany.com/blog/padparadscha-sapphires-a-buying-guide|url-status=live}}</ref>

This difference in color is based on the atomic structure of the stone. Although the different stones formally have the same chemical composition and structure, they are not exactly the same. Every now and then an atom is replaced by a completely different atom, sometimes as few as one in a million atoms. These so-called [[impurities]] are sufficient to absorb certain colors and leave the other colors unaffected. For example, [[beryl]], which is colorless in its pure mineral form, becomes emerald with chromium impurities. If [[manganese]] is added instead of [[chromium]], beryl becomes pink [[morganite]]. With iron, it becomes [[Aquamarines|aquamarine.]]Some gemstone treatments make use of the fact that these impurities can be "manipulated", thus changing the color of the gem.