https://www.vermontfurnituremakers.com/2016/06/wood-figured.html
Oddly enough, the tiger-stripe-like figure in curly maple may still feature a straight-looking grain. The wood waves perpendicular to a quarter or rift-sawn cut ..., so the unusual figure also runs perpendicular to the grain, but only in those cuts, just like medullary rays (also described in the first blog). Because the ends of the cell walls that are waving absorb light differently from the middle portions of the cell wall, the curly figure can also create “chatoyancy.”
Chatoyancy, an effect seen in some kinds of gems as well, isn’t figure exactly, since it’s more of an optical illusion. But, when brought out in a piece of Vermont curly maple (or other woods), it can make the waves of the figure really “pop” and is highly sought after. Because of the “differential refraction” of light, the waves appear to change in color and intensity when you move or change the lighting conditions, and can appear to dance on their own...