In the Hindu religious tradition, the tulsi, or holy basil, plant serves both as an important symbol and also as a popular medicinal remedy.
Diamond use to be the hardest known natural substance now it is the mineral lonsdaleite at 58% stronger then diamond is the first the second hardest is wurtzite boron nitridâ¦e at 18% stronger then diamonds they are both extreamly rare natural minerals sources http://www.newscientist.com/article/dn16610-diamond-no-longer-natures- ...
In terms of production costs, the most expensive substance in the world is antimatter. The cost of creating this material has been estimated at about $1,771 trillion US Dollars (USD) per ounce ($62.5 trillion USD per gram), although some authorities think it may eventually come down to a mere $141.75 billion USD per ounce ($5 billion USD per gram).