This sterling silver pendant features a highly unusual fragment of authentic "Graphic" black Roman porphyry. The marble exhibits white to green or light green inclusions arranged in a manner reminiscent of handwriting, inspiring its distinctive name. Sourced from the quarries that also produced red porphyry, this material was prominent in usage during the 1st and 2nd centuries AD.

Notably, a slab of this marble is on display in Rome, precisely within the right aisle of the Church of San Saba, providing a glimpse into its historical significance.