Original, one of a kind artwork in designer art jewelry by the Piro Group and Gregory Pyra Piro comes in mixed metal of sterling silver and 14 karat gold or 18 karat gold, or when it comes in all solid gold, Piro mixes yellow gold, green gold, pink gold, and white gold together which is only possible to do with soldering work, which makes the pieces one of a kind that cannot again be exactly duplicated.  It is not possible to mix metals with the process of casting, used to make production commercial jewelry with which it is only possible to make single metal pieces.  So pieces in multi metal such as designs by Piro are made more unique to stand out from the crowd from commercial production jewelry.  To make a multi metal piece, handwork or soldering by the artist must be involved.  Some pieces also have ebony wood mixed with sterling silver, and in some pieces also with 14 karat gold, which is a bit reminiscent in Piro design pieces from museums, which show his collections.  For gem stones, Piro design jewelry such as the watch bracelet above and bracelet below, mixes semi precious facet cut gem stones and precious facet cut gem stones.  Materials such as amber, ammonite, glass, sea glass, mother pearl, and pearls can be intermixed in the designs with amethyst, blue topaz, citrine, garnet, peridot, iolite, and tourmaline.  For little stones as accents in the designs diamonds, rubies, emeralds, sapphires are used in some pieces.