Almost everyone can wear Tiger's Eye crystal. Issues will only arise if you fall under a zodiac sign with a planet that clashes with those which rule this gemstone, the Sun and Mars. The Sun's enemies are Saturn and Venus and Mars' is Mercury. • Group: Quartz • Refractive index: 1.544-1.553 • Birefringence: 0.009 • Specific gravity: 2.65/ +0.03, -0.02 • Crystal system: Trigonal • Hardness: 7 • Inclusions: Chatoyance • Origin: Australia, Burma, India, Namibia, South Africa, the United States, Brazil, Canada, China, Korea and Spain