Women with an oval face can wear any style of necklace they desire, provided that the latter is proportional. If you are one, emphasize your long neck by opting for a choker or lengthen your torso with long strings of pearl. 
Yoko London, Masterpiece collection necklace 
 
 

Women with a round face need longer necklaces that lengthen the look of the face and draw the attention below the neckline. 
Cartier, Cartier Magicien high jewelry collection, Mandragore necklace 
 
 

Women with a rectangular face should wear short necklaces to reduce the lengths of their facial features. If you are one, opt for a princess necklace especially if you have a long neck. 
Bulgari, Fiore high jewelry necklace 
 
 

Women with a square face should balance their short features with a long necklace featuring round details to soften their strong jawline.
Chanel, Les Blés de Chanel high jewelry collection, Brins de Printemps sautoir 
 
 

A heart-shaped face calls for a short necklace with curves to reduce the long appearance of the jawline and the sharp points of the chin. If you have this face shape, a choker is also an ideal choice. 
Dior, Dior à Versailles high jewelry collection, Chambre de la Reine necklace 
 
 

A pear-shaped face is best complimented with a princess necklace that lengthen its look. Gentle curves are also a detail to keep a keen eye on, as they are essential to soften the strong jawline. 
Piaget, Sunny Side of Life high jewelry collection necklace