According to Vedic astrology gems have the energy of nine exoplanets. There are nine gemstones that we all called as Navaratna and of these people are associated together with the particular earth.
Now problem arises whether you are usually wearing gemstones for fashion or for astrology purpose. Thus firstly, you have got to be very clear with this thing.
In case you are using gemstones purely for fashion purpose then you could wear any gemstone. These days emerald green and sapphire gemstone necklaces are inside great trend thus you can use them.
On the other hand in case you are putting on gemstones for astrology purpose then a person should check with your current astrologer since this individual can tell a person the most effective gemstone based to your planetary position. It is vital to be able to ask from astrologer because sometimes incorrect gemstone can give you bad outcomes in life.