This is the 6379th most frequent Russian word.
цветом
"Цветом" means "by color" or "in terms of color."
In this sentence, 'цветом' is used to indicate the characteristic that the dress is exhibiting, emphasizing the aspect or quality of its appearance.
Её платье сверкает новым цветом.
Her dress shines with a new color.
Here, 'цветами' (instrumental plural form, related to 'цветом') shows the means through which the painting achieves its impressive quality—its vibrant colors.
Картина впечатляет яркими цветами.
The painting impresses with bright colors.
In this example, 'цвете' (another case form of 'цветом') expresses the characteristic of the design, specifically its stylish color aspect, showing that color can highlight aesthetic features.