Long Necklaces: A princess necklace usually measures about 18 inches and hangs just below the collarbone. 24 inch long necklaces are referred to as matinee length necklaces. These necklaces hang much lower of course, extending to the breast area. Opera length necklaces are even longer - 28 inches or longer. Rope necklaces are very long and can be worn as is or wrapped to create a two-stranded choker. Lariats are another style of a very long necklace, but they are unattached at one end so that it can be tied or knotted in different ways to suit your style.