The listing has ended... I dont think there is a thread for authenticating Loewes.
I've owned a couple. You'd need plenty of pics before making a purchase, such as the inner leather stamp, close ups of hardware.
You can also check the seller's feedback on www.toolhouse.org
It seems very pricey, anyway... I am confident you could get the bag for considerably less money at a store...
Try these websites... They sell authentic used loewes and i am sure they'd ship abroad http://www.bagdelux.com/Productos.aspx?col=3