All of the items I bought were used and had at least some small stain or sign of wear... one Winter haori in particular had a stain in the sky portion of it's very impressive hand painted scene on the inside lining - I chose to risk an aggressive washing - complete with Oxy gel - which explicitly states not to use on silk.
SO - Oxy applied on said stains. Wait 3 minutes - no change at all visually. 5 minutes - no change. I decide that's enough and ready a hot shower for myself, to which I would submit the haori since it also has some serious wrinkles after removing a long-stitch alteration for it's previous owner, and smells brutal of dry-clean agents.
In I go, and with me the haori turned inside out and on a hanger. I let the (hot!) water hit the oxy areas, and noted no change again except for some serious chemical smells from the dry clean chems coming out. Oh well, nothing lost or gained I assumed - I looked at the floor and WOW - why is the shower floor full of purple water?!!
I notice that the water rolling off the haori is a dark pink/purple color - and immediately dial in some cold water. I complete my rinse of the haori AND the shower floor - and let it hang overnight in the shower...
It was still damp in the morning, major wrinkles gone - and smelling much more neutral. I took it outside to air dry in the shade (your not supposed to sun dry silk, color can fade) while on the hanger.
All ended well - smells nicer, no wrinkles, but the stubborn stains will be in that painted lining's sky for life. Plus I learned that aggressive cleaning of silk should simply not be performed - even by hand! I got lucky, and that was some seriously runny dye.