Longer Necklaces:-
A princess necklace usually measures about eighteen inches and. hangs just below the collarbone.
1.Twenty-four inch long necklaces are sometimes referred to as matinee length necklaces. They hang much lower of course, extending to the breast area.
2.An opera length is even longer--28 or more inches.
3.Ropes are very long necklaces that can be worn as-is or wrapped to create a two-stranded choker.
4.Lariats are another type of very long necklace, but they are unattached at one end so that you can tie and knot them in different ways to suit your style.

Over time official standard lengths for necklaces were developed.

They have official, often romantic names:
Choker About 16" (40 cm)
Princess 18" (45 cm)
Matinee 24" (60 cm)
Opera 32" (80 cm)
Lariat or Rope 47" (120 cm) or longer.

As we see the length of the necklaces can vary from fitting closely around the neck to reaching the hips. In choosing a necklace, particularly the shorter lengths, it makes a great deal of difference whether the neck is small, medium, or large. To wear a short necklace just around the neck, its length has to vary from 15" (38 cm) till 24" (60 cm)! depending on the measurements of the lady. Your neck size can be accurately ascertained by placing a piece of cord around the base of the throat- it should meet but not be drawn tight- and than measuring the cord by a measuring tape. If necessary, ask for help.

Chokers and short necklaces are often made with extension chains to fit any size neck.
These extension chains are very practical but they have a disadvantage: The chain will elongate only one half of the necklace, so the clasp will not be centered anymore in the neck. This can cause problems with a necklace which is strung in a symmetrical pattern. Furthermore, a part of the necklace will be replaced by chain, which interrupts the continuity of the beads in the neck and makes it less beautiful, especially with a short hair-dress.

If you do prefer a certain type of length, just measure your favorite necklace with a household measurement tape, do not forget the extra length provided by the clasp and its surrounding. Write it down and put the little note in your purse.

A short necklace like Chokers, fitting closely around the throat, takes the form of a circle, a longer necklace like Princess, takes a V form and fits often beautifully an open blouse. A length of 32" (80 cm) or more is often problematic for the fuller bosom, because the necklace will take its place or between or around the breasts. In a funny way the actress Julie Andrews shows this in de film "Thoroughly modern Milly". This film is situated during the "Roaring Twenties", the time of the Charleston, when the so called flapper bead necklaces of even 60" (150 cm) of length and a flat bosom, provided by the "Garconne look" (Boyish look) were the trend.

A necklace up to 24" (60 cm) will need a fastener, anything over that length will go over the head without opening it. If a necklace longer than 24" (60 cm) does have a clasp, open it when you want to put it off. Your hair will entangle in it while removing the necklace. This is less a problem when putting it on. With a fastener a necklace of 32" (80 cm) will go twice around the neck and with a length of 48" (120 cm) three times (if desired). Without fastener the latter is only possible twice.