38-43 cm. So that it fits around the neck, not tight, nor too long.

It's a necklace that fits tightly around the neck. It can be a chain or a rigid necklace.

Necklaces measuring 75-85 cm that you can wear as is, as a long necklace, wrap it around your neck twice, or use it as a belt.

It could be a sailor clasp, for example, on which you can hang charms.
These necklaces can be worn with the clasp in front (to show off the clasp and/or what hangs from it) or in back to show off the chain alone.

It is a Y-shaped necklace, a chain hangs from the center making the shape of the letter.

It involves combining different sizes, colors, and shapes of necklaces to complete your look. The more necklaces you combine, the better the look.