how can i identify "real" UV filtering sun glasses from fake ones without specific tools?

To check for a polarised lens take a watch (digital) and hold the glasses in front of it. Rotate the glasses through 90 degrees (top becomes side). The display should disapere or some of is should dissapear.

Excessive exposure to ultraviolet radiation (UV) can cause short-term and long-term ocular problems such as photokeratitis, snow blindness, cataracts, pterygium, and various eye cancers[2]. Medical experts often advise the public on the importance of wearing sunglasses to protect the eyes from UV[2]. In the European Union, a CE mark () identifies glasses fulfilling quality regulations. In the preparation for solar eclipses, health authorities often warn against looking at the sun through only sunglasses.

There's no demonstrated correlation between high prices and increased UV protetection. A 1995 study reported that "Expensive brands and polarizing sunglasses do not guarantee optimal UVA protection." [3]. The Australian Competition and Consumer Commission has also reported that "[c]onsumers cannot rely on price as an indicator of quality" [1]. One unscientific survey even found a $6.95 pair of generic glasses with slightly better protection than Michael Kors or Salvatore Ferragamo shades [2].

More recently, High energy visible light (HEV) has been implicated as a cause of age-related macular degeneration[4][5], and some manufacturers design to block it. Sunglasses may be especially important for children, as their ocular lenses are thought to transmit far more HEV light than adults (lenses "yellow" with age).

Some sunglasses also pass ANSI Z87.1 requirements for basic impact and high impact protection. These are voluntary standards, so not all sunglasses comply, nor are manufacturers required to comply. In the basic impact test, a 1 in (2.54 cm) steel ball is dropped on the lens from 50 in (127 cm). In the high velocity test, a 1/4 in (6.35mm) steel ball is shot at the lens at 150 ft/s (45.72 m/s). In both tests, no part of the lens can touch the eye.

It turns out that most glass and plastics are good UV filters with out any treatment. I had a professor who did a study for that very purpose and found that sunglasses from supper cheap to expensive block UV adequately. The reason that they all claim to do this is that they all do , it seems to be the general nature of plastic and glass, but they'd rather you think that its some sort of special treatment they do to the sun glasses.