Step Four Ponder the face shape of your intended recipient. Purchase round or triangular pieces for an oval face; square, oblong or rectangular earrings for a round face; and triangular earrings ...
When you?ve chosen the correct style of earrings, Gold advises having your customer put one of them on one ear and place an unflattering earring on the other.
Buying Guide -
http://www.professionaljeweler.com/ archives/articles/2001/feb01/0201fys1. html
Consider the geometry of her face and what will accentuate her good features. The texture and the color of the earrings should work with the cut and color of her hair.
Buying Guide -
http://www.professionaljeweler.com/ archives/articles/1999/jun99/0699fys6. html