Diamond prices are not only affected by the shape type (i.e. pear, marquise, round, etc.), they're also affected by the attractiveness of the chosen shape. For example, an unsymmetrical or a long and skinny marquise diamond can't command the same price as a well-shaped marquise. The following diagrams show desirable shape outlines of five basic shapes. A knowledge of the ideal round shape is assumed. If you are buying a diamond for your own personal pleasure, its shape doesn't matter, as long as...