These chains are woven by (my) hand using a metal tube (to ensure the loops are uniform in size).  The pearls are pre-drilled as beads and inserted on the chain as it is woven so they are totally secure.  There are many colors of small pearls available so I can produce many combinations of pearls and wire.  They have a 1" of chain on one end so the length is adjustable.  The 18k and 14k chains are more expensive because of the gold and the fact that their adjustable chains are handmade (by me) from wire and are not commercially available.