These necklaces are called chachales. They are ceremonial necklaces used by people in the Mayan cultures of Guatemala. Chachal means necklace in the k'che language and is also a reference to the sound these make when they move.
This necklace is entirely handmade. It features pairs of animals including fish, quetzales, some water birds (probably ducks, deer, horses, pigs, rabbits and another type of diving bird. It also features replicas of mayan and spanish coins. It was sold to me as silver, which is not to say that it is solid sterling! I don't know silver content.
It is about 25 inches long. It weighs about 12 oz.