There are several color gradients that appears in almost all RO color tables.
Those are known as the RO common colors, and their use is recommendable for
all new spriters (this way they will avoid making saturated or bright
sprites).
Those colors are shown in the next image.
At the bottom part of the image, we can see some solid colors, that are used
as reference colors. Before coloring the sprites, we have to make the edges.
Many spriters use these solid colors to make the edges since they are more
visible than common RO colors.
There are certain sprites that don't look good with RO common colors and need
new color gradients. An example is bronze color. It is a kind of bright brown
with a bit of green. This color doesn't exist in RO and must be added to the
color table by us.
On the other hand, there are several colors such black that appear only
applied on certain sprites. There are more colors, like pink, gold and ice
blue that appears on some sprites.