What exactly gives precious and semiprecious stones their “identity”?

Question

I’m used to classifying stones by their color (i.e. purple=amethyst). How is it possible to have pink sapphires or blue topaz? Is it the internal structure of the stone?

In: Other

Answer 1

Generally it is chemical impurities in the crystal structure which alter the colour of the stone, while keeping the general crystal structure and properties the same. So the colour of rubies and sapphires is governed by trace impurities within the main mass of aluminium oxide or corundum, with chromium oxide producing a red ruby, iron and titanium producing a blue sapphire and vanadium producing a purple sapphire. https://youtu.be/63bLM5dWmgA