There is a gem stone that relates to each of the nine planets. These nine stones are called Navaratnas (nine gems). Five of them are categorized as Maha Ratnas, and are considered superior. These are diamond, ruby, emerald, blue sapphire, and pearl. If the better quality stones are too expensive, it is all right to wear a good quality substitute, but the higher the stone’s quality, the stronger the effect. Planet Primary Gemstones Secondary Gemstones Zodiac Sign Sun Ruby Red Spinel, Red Garnet, Red Zircon Leo Moon White Pearl Moonstone Cancer Mars Red Coral Carnelian, Pink Coral, Bloodstone Aries Scorpio Mercury Emerald GreenJade,Peridot, Green Zircon Gemini Virgo Jupiter Yellow Sapphire Yellow Topaz, Citrine Quartz Sagittarius Pisces Venus Diamond Clear Zircon, Quartz, ClearSapphire Taurus Libra Saturn Blue Sapphire Lapis Lazuli, Amethyst Capricorn Aquarius Rahu Hessonite Garnet Golden Garnet, Orange Zircon, OrangeGarnet Ketu Chrysoberyl Cat’s Eye Other types of Cat’s Eye Tiger Eye, Beryl
Planets Relation

(via Eastern Gemology)