The spread of new metal technologies in the Neolithic Era was mostly caused by which group of people?

The goldsmith reached a state at the level of primary Fine Arts in Greece. To the manufacturing processes of the embossing, chiseled and filigree already known in the previous civilizations, the granules were added by the Greek artists, sowing the surface of the piece with gold beads by an unknown procedure. But long before the Greeks already practiced the Egyptians because they have been found in jewels of dynasty XII