You've seen leaves with multiple colors on them, often different ones.
This variegation can come from a few different sources. Chimeral variegation comes from two types of plant tissue that alternate in one plant. These plants are from a mixed genetic makeup.
Reflective variegation happens when a layer of air is sandwiched in the leaf surface. It tends to cause a white or silver reflection of light. If you like a variety of variegation, consider variegated weigela in our online plant nursery.
Source of Information on Variegation