Sergey I have rarely seen fire when people are wearing earrings or pendants.
Do others see fire in those cases? Maybe only in very large stones?
grab a ruler, place one end between your eyes. slide your finger along (use specs/contacts if you wear them often). If you can focus closer thaan 10 inches 25cm then you may find the stone appears a little dark on close innspection. If you are short sighted and can focus less than 6 inches 15cm then its not for you