Lovely example of a gold filled long chain, with replacement clip (originally was likely to have a dog clip instead of this slide open clasp). The opal slide has a blue flash opal stone, although likely glass, set in the center of a square slide in gold fill. It moves along the chain to adjust to how the wearer chooses to adorn their neck.
These long chain necklaces are very versatile - you can double them up or wear them multiple ways, with the slide being able to move up and down the length of the doubled up chain.
Length of chain doubled up is 25 inches (as shown from clasp to midpoint). Full length from start at clasp to end at clasp would be 50 inches. Total weight is approx 11.27g.