Our 3 Stone Asgard Necklaces are constructed using the chainmail weave 3-1 Half Persian and are made of anodized aluminum and so contain no lead or nickel. They can be ordered in a wide variety of colors or you can contact us to do custom colors. The rings are 16 gauge 5/16" rings. At this time these are the only stones we can use in this weave. 18" is the standard length for these pieces, if you need a different size please just contact us and let us know.