唔該.....又係gucci問題

The gucci could have different colour of strap. However, without seeing your friend's bag it is very hard to tell if her bag is authentic.

but $1900?
That bag is about $4200 to $4800 (depends on the size) and if your friend got it on sale then she probably paid $3000 - $3600.

I would suggest you to go to those 米蘭站 or 巴黎站 to have a look to see if they sell the bag that you are looking for and check how much they sell. At least you know if you are paying too much for a second hand bag.

Btw, is she a good friend to you? If she is a v. gd friend of you then she shouldn't lie to you. But 人情是人情, 數目必須分明.

I personally think the best is you & your friend go to 米蘭 together to ask the people in 米蘭 to quote the price of the bag. Tell your friend you are happy to pay few hundreds more than what they quote but not more than the same style secondhand bag you can find in 米蘭. In this case you can be sure the bag is real and you can buy the bag in the right price..(WARNING: Don't do it if your friend is very 小氣 )