Apple coral beads are cut from stabilized red sponge coral. Like all sponge corals, apple coral features visible pores (like a sponge) when polished. While apple sponge coral is naturally a dark brick red, red dye is sometimes added to the stabilizing resin when these semiprecious beads are made. These coral jewelry components might lighten with exposure to heat or extended direct sunlight. Coral is among the most ancient of gemstone materials, used for adornment since prehistoric times. Coral inlays and ornaments have been found in Celtic tombs from the Iron Age (500 B.C.-400 A.D.). In ancient China, red coral was a symbol of wealth, favor and high social status. Coral is one of the seven treasures in Buddhist scriptures, and Tibetan lamas make rosaries with coral beads.