According to my experience only natural gemstones can give the benefits and according to Vedic astrology our 9 planets represent, the 9 special gemstones , Ruby represents the sun, pearl the moon, coral the mars, emerald the mercury, yellow sapphire the Jupiter, diamond for Venus, blue sapphire the Saturn, hessonite the Rahu and cat’s eye  for Ketu. Its necessary to know about the gemstone you are going wear if that is going to give good or bad effects according to your horoscope, Otherwise, in the case of opposition, that can also do harm rather than benefit. So if you want to wear a gemstone do consult an experienced astrologer before you wear them.