Although there are no set rules and a lot depends on the personal taste, experts believe the best way of positioning catchlights is using the clock rule. Imagine the eye as a clock and think of an hour hand pointing at 10 o’clock or at 2 o’clock and you’ll get the two perfect positions for a catchlight. (Bright Hub Inc)

Multiple catchlights, evident in magazine cosmetic ads, add sparkle to the subject's eyes. The angle of the strobe produces a catchlight in that spot in the eyes; i.e. high to the left of camera gives about an 11 o'clock position of the catchlight in the eye. (BetterPhoto.com, Inc.)

The catchlight is fairly large (given the size of the modifier) and shows the modifier's rectagular shape. It's got fairly soft edges, though, so it's quite pleasing. The larger softbox gives a larger, less distinct catchlight. (Don)