Many of the necklaces I design are available with a custom chain length. This means you can choose the best length for you or, if it's a gift, then a length suited to the person that you're buying for.
Often the best way to decide on the ideal necklace length is to measure a chain from something already owned that you like. It's important to include any clasps ends and tags in your measurements as well.
You may want to consider the pendant size too. I give measurements for all of my pendants so you can see if it's a dainty or a more weighty piece. Small pendants lend themselves to shorter chains up to about 24 inches in length. Larger pendants (like terrariums for example) should really sit below the sternum at about 24 inches or longer. There are no rules though, so please choose what's best for you!
The diagram above is a guide and indicates an average fit for a woman. I hope to include one for men soon. Please also consider your height and build when making your selection.