@Helen,
Females are advised to wear their rings in left hand while males are advised to wear them in right.
You can wear blue sapphire along with garnet but not with ruby as per the list shown above this post.
In India, people don’t take the rings off from their fingers as they had worn the gemstone on special day after worshiping. And they believe that taking the rings off could lessen the astrological powers.
But, one should not be worried about taking the ring off if one feels uneasy with it. It is just about one beliefs. But for full astrological effect it should be worn 24/7/365. If you can’t wear it through out the day, specially on night then keep the ring under your pillow.
In India, before wearing a gemstone either a ring, pendant, etc., astrologers advise to keep the gemstone under their pillow for 3-4 days when going to bed to see if the gemstone brings positive result.