Definitions for "Opera Length"
refers to a pearl necklace 28 - 36 inches (70 - 90 cm) in length.
a pearl necklace 32 inches long.
An opera-length necklace is a single strand that is from 60 to 90 cm (30 to 35 inches) in length. Opera-length generally refers to a string of pearls that hangs to the breastbone.