How do you tell the quality of metal on your zippo lighter?

the bottom of the outside will have Zippo on it and the inside on the side of the guts when you pull it out will say zippo all zippos have zippo on them

Shenshang:

The insert of the lighter is fake if the flint wheel and other bits starts going brown or blue or green, it means they have iron or copper additives which zippo do not use. Also check the case and most fake lighters have the lid and case which do not match and the bottom doesnt say what a real zippo says, an example of what a real one says is:

"B ZIPPO 07
BRADFORD.PA. MADE IN U.S.A."

Hope it helps.