Purple used as a color of beauty and femininity.
It's certainly pretty on these Princesses.These days, some cultures see purple as a feminine color, perhaps the most feminine color, other than pink. Then again, it's not always the same kind of femininity as pink. This is seen often as the more "graceful" and "mature" color, while pink often is the more "sweet" and "girly" color. But not always. Now even though this color can be worn by girls of any age, older feminine women are more likely to wear this color long after they stopped wearing pink. So you could say Princesses Prefer Pink, but a Proper Lady prefers violet. This also tends to be a popular color among some Mary Sues. A Sister Trope to Pink Means Feminine (and can double it with colors like fuchsia). Compare Purple Is Pimp (and can overlap if the wearer is an Action Girl, but still in elegant clothes), Purple Eyes, Princess Phase, Purple Is Pink On Steroids.