Walter Earl Morrison, 20, of Phoenix, Az., was charged with felony theft after he allegedly stole a package containing the diamond while unloading a UPS cargo plane, authorities told ABC's Phoenix affiliate KNXV-TV.
The diamond was valued at $160,000, according to KNXV-TV. That's enough money to buy a Maserati sports car and still have enough left over to make a down payment on a house.
But Morrison had different plans.
He traded in the $160,000 diamond for $20 worth of weed, which according to a global marijuana price index is the rough equivalent of two joints.
A spokesperson for UPS told KNXV that the diamond was recovered and delivered to its intended customer. Morrison was fired.
Morrison is scheduled to appear in Phoenix' Maricopa County Superior Court on Tuesday.