Deep hues available in various colors (SHOP NOW).
And there are so many tricks and techniques to expand the color range using just the marker colors offered!!
One of these is using gray as a shading color.
Here I used the stamp set, Wavy Blooms (D1651),
The center of the petals and any petals underneath another where you might find a darker shade was colored using ShinHan Warm Grey #4. Adding a darker yellow/orange, ShinHan Marigold and finishing with ShinHan Golden Yellow. While coloring the full petals, I left certain areas in the middle white. I set the work aside and let it dry and then came back with the Golden Yellow again and, as you can see, there are some light areas.
Here is the video I used to learn this technique