Short form: In order to harden sterling silver, you must heat it to 535 degrees F. and then cool it to room temperature over a long and specific time span.
History:
The original research on this subject was done as an MIT doctorate thesis by Morris Cohen in 1936, and was published in the Transactions of the American Institute of Mining and Metallurgical Engineers in 1937, pp. 124, 138-157.
Excerpts:
