Types of Coral Stone - A Complete Guide Coral is a type of organic material that is found in various shades such as pink, orange, red, and white. There are different types of coral stone corresponding to a particular color, pattern, and look. Unlike other gemstones, coral is an organic gemstone, similar to pearl and amber, meaning, we need to show gratitude to living organisms for creating them, rather than thanking some arbitrary geological process. Coral is also one of the Navratnas. Navratnas is basically a group of nine gemstones that possess astrological powers in the context of Vedic Astrology.