French 18ct Gold & Silverium Cartier Hoop Clip On Earrings In Original Cartier Case

A good pair of hoop earrings by Cartier, Paris that were made in the late 1980s onwards. They are 18ct75% pure gold (or 750 parts pure gold and 250 parts other metals) gold with Silverium which  is a 1987 process trademarked by Cartier.  Silverium is a type of blackened silverA metallic element which is malleable and ductile, and white in colour, making it ideal for use in jewellery. It is usually mixed with copper to improve its hardness.
that is alloyed with 18ct gold.  It was originally designed for the company’s mascot, the black panther to achieve the shiny black coat. It then led to several jewellery styles and this pair of earrings is part of the collection