smoke-tinted

[keannu]

What does this "smoke" in "smoke-tinted" mean?

is140
ex)...The process by which sunglasses have gained worldwide popularity is a fascinating one that began, surprisingly, in the justice system of medieval China. Dark glasses with smoke-tinted quartz lenses existed for centuries in China priot to 1430, but they were not used for sun protection...

 

[BobK]

I imagine it's a bad translation. Glass can be smoked; glasses can be tinted.

b

 

[SoothingDave]

Maybe they used smoke to impart a layer of residue on the glass to make them tinted. That would be my guess.