Counterfeiters regularly offer Ray-Bans at a major discount. At best: people receive knockoffs. At worst: nothing at all.

During the sales season in France, thousands of French people recently received offers for Ray-Ban frames for less than 20 euros ($31). This fall, they were invited on Facebook to a charity event. A Facebook page called Société Ray-Ban was offering frames for 24 euros ($37) and promising to give half of that amount to charitable organizations.

Both offers are scams, just like the ones that cropped up in 2014 in Canada on the raybanca.com website (a Chinese website), offering $26 liquidation Ray-Bans, or the $29 frames regularly announced on Facebook.

In response to these scams, Luxottica has created a Facebook page where you can report fraud cases or scams related to Ray-Ban and Oakley brands: http://www.luxottica.com/en/help-center/report-fake.