Koi can be more expensive than others of the same size because of many different factors, mainly color and pattern. The colors on a more expensive koi will tend to be deeper and more vibrant. A koi that has deep red or jet black will be more desirable than a koi with fading red or light grey spots. This can also apply to the pattern of color. The pattern must be evenly distributed throughout the body, without too much color concentrated on one end or side of the koi. Usually, an expensive koi, as compared to another the same size, will have a visually pleasing and balanced pattern, with deep, dark colors.