Coral's earliest known use in jewelry dates back 30,000 years. Coral is soft compared to most gems. All corals require certain environmental conditions for growth. The water must be fairly calm, it must be within the right temperature range, and it must be free of pollutants and suspended mud. These conditions only exist in a few geographical areas. In Vedic Astrology, Red Coral is worn for planet Mars. It imparts courage and helps in overcoming fear and nervousness in the individual. • Group: Coral(Calcareous) • Refractive index: 1.486-1.658 • Birefringence: 0.172 • Specific gravity: 2.70/ +0.05, -0.5 • Crystal system: AGG • Hardness: 3.5-4 • Origin: Italy