Size your cuffs and bangles to fit snugly, and your link and chain bracelets to fit slightly loosely to allow for movement.

Use a flexible measuring tape or length of string.
Wrap it around the thickest part of the wrist (usually at the wrist joint). If using string, mark the point on the string where the ends meet with a pen. If you are creating a bracelet stack, measure the point on your arm where you’ll wear each bracelet.
Lay the string on a flat surface and use a ruler to measure the length (in inches or centimeters) up to the mark. Compare your measurement to the Tiffany size chart above to determine your bracelet size. If you are between sizes, opt for the larger size.

Necklaces vary by chain length. The circumference of your neck and size of the pendant will impact how your necklace sits on its own and with other styles.
Measure and cut a piece of string to the same length as the necklace you’re interested in.
Place it around your neck to see where it falls—the key to layering is striking the right balance. Consider the size and shape of the pendant.
Repeat the process to see how necklaces of different lengths may look together.