Necklaces will sit differently from person to person because all our necks are different thicknesses. Sometimes a diagram can be misleading.
Measuring the length you'd like around your neck is the best way to determine which size to choose. Take a string and measure that against a ruler, or use a measuring tape. We offer multiple sizes, so choosing various lengths allows you to create a layering look.
If you're buying a gift, our 18-inch necklace is a great "one size fits most" length.