Hello Sitra Ahra. I`m not sure if this material would suit your requirements -
Art Clay UK: Silver clay, courses, books, fine silver findings, stones, tumblers and kilns for metal clay.
It does give you more of a working time than when using molten silver etc, though. That is, if you were using a metal. I once managed to carve a fine ring from out of bog oak, which is almost as hard as metal itself! There are plently of decent jewelry makers out there, sure the other members can give you some good pointers here. Good luck though, nothing quite like that `unique piece` is there.