Collar — 12/13 inches
Collars are usually made up of three or more strands and lie snugly on the middle of the neck. Very Victorian and luxurious, collars go best with elegant V-neck, boat neck or off the shoulder fashions.

Choker — 14/16 inches
A choker is perhaps the most classic and yet versatile of all the single strand lengths. A simple choker can go with virtually any outfit from casual to fancy evening wear, and just about any neckline imaginable.

This is a good necklace length for a child. This way the necklace has "growth room".

Princess — 17/19 inches
The princess length necklace is best suited for crew and high necklines. It also complements low plunging necklines.
Hint : it is a perfect support for a pendant.

Matinee — 20/24 inches
Longer than the choker, and just a bit shorter than an opera length, the matinee necklace is the right choice for casual or business dressing.

Opera — 28/34 inches
The opera necklace is the queen of all the lengths. When worn as a single strand, it is refined and perfect for high or crew necklines. When doubled upon itself, it serves as a versatile two strand choker.

This is the most common length for a necklace.

Rope or Lariat — Over 45 inches
Dripping with elegance and sensuously sexy, the pearl rope was a favorite of Coco Chanel.

Clasps placed in strategic locations around the necklace will enable you to break it down into multi-strand necklace and bracelet combinations.

For those looking for the complete wardrobe, this length is a must.
Lariats are at last 48 inches long, with the ends left unattached for knotting or wrapping around the neck.