Diamond

Most hard in appearence but the most tender in feeling .It is forever.It is the hardest of all gemstones . Its hardness is 10 on mohs scale.Its refractive index is highest so total internal reflection is possible at minimum critical angle, the reason for its most brightness.The parameter for its quality is "4c" i.e,colour,carat,clarity and cut and 5th 'c' is our credibility. It gives luxuries, romance, beauty, sex appeal, charm, guarantees no divorce in marriage, cures sexual diseases and infertility.
source - South Africa , India(Golkunda), Zaire, Brazil. planet-venus rashi-Tauras(vrisha),Libra(tula). metal-silver,platinum. Mantra:- Oum hreen shreen shukray namah.