@Sanjay, (click here to view Sanjay’s question)
According to astrology, plant relationship (Graha maitri) is there. They are classified as friends and enemies.
SUN has friends – Moon, Mars, Jupiter and Enemies – Saturn and Venus.
So, this might be the reason that one should not wear RUBY (SUN) with BLUE SAPPHIRE (SATRUN) as both have enemy relationship.