The price tag for a product is generally interconnected to the hardships of producing it, which essentially makes their value per gram very high.
At the top of the list are typically a combination of extremely rare metals, radioactive isotopes, and gemstones. The most expensive substance, Californium, is a radioactive element first made in 1950. The value, which is in the upper echelon, breaks the bank at $27 million per gram.
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Other familiar metals on the list include the platinum group metals (PGMs), platinum, palladium, rhodium, and iridium, all of which range between $16 to $27 per gram. Also making the list is gold, which is worth just under $34 per gram.