The direction of a ricochet:
The sharp edge of the "comet" is where the bullet first struck the surface. The tip of the "comet" points in the direction that the bullet
was traveling. The bullet above is going from right to left.
The direction of rotation or twist:
Bullets that ricochet off of glass and other non-yielding, smooth surfaces at low angles will leave a tail indicating the direction of rotation. In cases
where there were multiple guns fired, the direction of rotation could often give clue to which gun the ricochet was fired from. The image above is a ricochet from a gun with a right (clockwise)