On the hot pressing of coloured high-gold alloys powder compacts applied to the manufacturing of innovative jewellery items

Innovative design through colour has always been a very important feature in decorative items, jewellery inclusive. The use of coloured gold alloys (e.g. red, white, green) in the manufacture of jewellery artifacts is nowadays generalized, and one can often see jewellery items that combine more than a single colour. However, multi-coloured jewellery artifacts are generally made of parts produced separately and bonded together in a later step. The ability to produce jewellery sub-components or final pieces using a powder metallurgy process aimed at producing innovative multi-coloured gold jewellery items with colour gradients is explored in this paper. Four 19.2 ct coloured gold powders (yellow, green, red and white) were hot pressed at different times and temperatures and the resulting samples were analyzed in terms of their microstructure, hardness, porosity, microstructure and optical properties. A manufacturing route to obtain multi-coloured jewellery pieces with colour gradients is also presented.