Since this was my suggested prompt, I will try to clarify what I understand by "chiaroscuro".I'm not sure "chiaroscuro" will ever grab me!
First, a dictionary definition:
"The use of deep variations in and subtle gradations of light and shade, especially to enhance the delineation of character and for general dramatic effect: Rembrandt is a master of chiaroscuro."
Second, a couple of examples:
Chiaroscuro by ramirezaponte, on Flickr
Guitarra by ramirezaponte, on Flickr
Hope this helps!