Spangold

Spangold is a family of shape memory-effect alloys (SME) of gold, copper, and aluminum in either 18K or 23K which, when heated and cooled correctly, results in a multi-colored faceted finish which is appealing as jewelry. The name of the family is a play on the word "spangled".

Spangold is a beta-phase alloy with a nominal stoichiometry of Au7Cu5Al4 and a nominal composition by mass of 76% gold, 18% copper, and 6% aluminum. The texture is caused by the induction of a martensitic-type phase transformation on a polished surface.

The key to Spangold's unique texture lies in its ability to undergo a martensitic-type phase transformation when properly treated. This phase transformation is induced on a meticulously polished surface of the alloy. Martensitic transformations are a common feature in shape memory alloys, and they involve a reversible change in crystal structure that allows the material to recover its original shape when subjected to specific temperature changes.

In the case of Spangold, the transformation results in a surface that appears to be adorned with multi-colored facets. These facets give the alloy a captivating, ever-changing appearance, depending on the angle of light and the viewing perspective. This striking visual effect makes Spangold an excellent choice for creating unique and eye-catching jewelry pieces.

Jewelry designers and artisans often appreciate Spangold for its versatility and the potential to create one-of-a-kind pieces that are both visually stunning and technically intriguing. The alloy's ability to "remember" and return to its original shape after being deformed under certain conditions adds an additional layer of fascination to its use in jewelry design.