It is similar to "making it rain", except that instead of throwing dollar bills, one is so rich that they are able to throw diamonds. In effect, making it snow. Diamonds can be substituted for a large quantity of cocaine.
Similar to "making it rain" by throwing dollar bills, but because one cannot afford to throw dollar bills, they throw pennies or nickels instead. Making it drizzle also puts less of a dent in your wallet and is usually practiced by those who have not made it big time yet.