where sterling silver can be greatly hardened by heat treating.
to do this you first heat the sterling to 750C (1382F) and hold
it at this temp for 30 minutes then rapidly quench the item is
then heated to 300C (572F) for 1 hour. this will result in a
sterling piece that has a hardness of 110-120 Vickers and a
tensile strength of 350 Nmm -2. The heat treatment can only be
done on items that are NOT soldered as 750C will melt all
silver solders if the item has been soldered prior to treatment
and soldering after treatment will anneal the item and remove
all the hardness gained.