Page "Gemstone" Paragraph 40

The same material can exhibit different colors.

For example ruby and sapphire have the same chemical composition ( both are corundum ) but exhibit different colors.

Even the same 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 sapphire ".