According to this curious chart, drugs and diamonds are by far not the most expensive substances on our planet.

Saffron – 11$/gram

Gold – 56$/gram

Rhodium – 58$/gram

Platinum 60$/gram

Methamphetamine – 100$/gram

Rhino horn – 110$/gram

Heroin – 130$/gram

Cocaine – 215$/gram

LSD – 3000$/gram

Plutonium – 4000$/gram

Painite – 9000$/gram

Taffeit – up to 20000$/gram or 4000$/karat

Tritium – 30000$/gram

Diamonds – 55000$/gram

Californium 252 – 27 million $/gram

Antimatter – 62.5 trillion $/gram