The length is a key factor in determining style. Different lengths will be appropriate for different people and places of wear.
Thickness can also determine the style of a necklace, as well as the presence and size of a pendant. These are both things to consider when choosing the perfect necklace. A thicker chain will tend to be heavier and may not be suited for a very long necklace, and a low-hanging pedant will lengthen the appearance of the necklace.