U know very well there r too much difference in the men to men’s gravities of planets. Just I want to explain about it.
Low & high gravity of gems may affect your life's activities while accurate gravity of gems will be 100% perfect gems for you.
The toughness & flexibility is calculated by the combination of degrees of your planets, nakshatra, charan, planet is situated in which rashi. etc
Each and every planet has their own responsibilities given by nature to your life.
Why Astrologer advice to wear gemstone because of the weakness of your planets.
If The dasha-antardasha-pratyantar dasha is weak it means that the time duration of your life will be panic, tensionful life, financial problem ( less income & high expenses) etc, it means the gravity of that planet is not perfect. But it is the subject of verification that is how much gravity is needed to your planets in horoscope.
Lastly, it is my humble request that before purchasing the gems,you must verify it’s gravity by the perfect Astrologer.
Note:- it's a fact that the shopkeeper knows only the price and originality of stone but he can’t verify the gravity of your planet which is situated in your horoscope.