Silver, white patina?

Happy Holidays to all,

I’m not sure what the proper term is to ask for some how-to advice
on this so here’s a rough description… What is it called when
you have sterling silver that’s been engraved, stamped, etc. and has
been blackened with ie; liver of sulfur, but the surface of the
silver is white? As in fresh-outta-the-pickle-pot white. And how the
heck is that done without losing the black areas? Really stumped on
this one.

Seems that someone may have discussed this a year or so ago but I
must not be using the right keywords while info-mining the archives
to find it. I sure would be appreciative of any help anybody can
offer on this.

Thanks so much, Carol