3.5 is not enough. Make sure it has 3 strips on the port thing.
Check this -
The first one is an iPhone headphone which doesnt work. The middle one is a Skullcandy one and the third one is the stock. As you can see middle (skullcandy) one has only 2 stripes whereas the stock one has 3. Because of this the skullcandy one give crappy sound on the G3.
WRONG INFO!
the third strip is only required if the earphones have a mic....
also skullcandy gives amazing sound on g3....
i have 2 pairs (skullcrushers and uprock) both give amazing sound.
if the headphones have a mic then it will have 3 strips .
if they dont then only 2.....
wether they have 3 or 2 strips does not affect sound quality at all....
3.5mm is standerd and any earphone with this jack will work on our phone with its best sound quality....
but sometimes the mic may not work due to different standerds...
but as such all headphones itself will work perfectly.....just the mic can be tricky.... also 90% of high quality headphones wont have a 3rd strip cause they are made for listening to music and movies and not as handsfree devices...