Natural Red coral with White Keshi Coin Pearl Stud Earrings. Red coral is an organic gemstone with properties of a \(3.5\) on the Mohs hardness scale, making it relatively soft. It is a calcium carbonate composite, known for its vibrant red color and associated with symbolism of vitality, energy, passion, courage, and protection. It is used in jewellery and believed to have therapeutic and astrological benefits, such as improved circulation, increased energy, and protection from negative influences.