Can gemstones lose their colour?

Yes, certain gemstones can permanently lose or shift their colour over time because of long exposure to direct sunlight, high heat, or strong cleaning chemicals. This effect, commonly called colour fading or bleaching, happens a lot in particular light-sensitive minerals.

For example, kunzite, amethyst, and some types of yellow topaz, plus pink tourmaline, have colour centres that are not very stable. They respond badly to ultraviolet (UV) radiation from the sun, and their vibrant tints fade for good. Other stones, such as oil-treated emeralds or dyed agates, might look like they completely lose their colour when the oils, synthetic dyes, or resins used for enhancement dry out, or when they get loosened by household cleaning agents. To keep a gemstone’s original colour, it should always be kept in a dark, temperature-controlled setting, away from direct UV exposure.