彼女は華やかなドレスを着てパーティーに現れた。
She appeared at the party wearing a gorgeous dress.
The venue was decorated with brilliant ornaments.
prosperous; flourishing; thriving
Used for a lively, successful, and thriving state, often in contexts like careers, social scenes, or historical periods. Less common than the visual sense.
He has a brilliant career.
This town was once a flourishing commercial center.
She stood on stage wearing a gorgeous costume.
When Christmas season comes, the streets become bright and festive.
He is a businessman with a brilliant career.
The entertainment industry looks like a glamorous world, but a lot of hard work goes on behind the scenes.
華やか describes something bright and showy in general, while 彩り specifically points to the touch of color or visual vibrancy something adds.