How can you spot fake Versace/DG Sunglasses?

I was gonna get a pair from this guy for a trade how do you spot if there real or fake?|||You look at them, and if they don't have numbers on the inner rim, they're fake. I wouldn't buy designer glasses from ''some'' guy. You never know if they're fake or not. Nordstrom Rack has cheap Versace and DG sunglasses. I got a pair of Versaces from there for $70.