The G13 is an outstanding pure Indica cutting reputedly discovered by the U.S.government research program in Mississippi when they were looking for a ideal medical strain for cancer patients.
However.....true G13 does not exsist on the commercial market today. Often times dealers will drop the G13 name just to sound fancy and mark up the price.
Soooo....my advice is......if it's good weed, it's good weed....who cares what it's called.
If it looks nice and fluffy and dank, smells good, tastes good and has a good high it's probably grown in organic soil....if it looks nice and fluffy and dank, tastes funky and has a strange after taste it might have been grown with chemicals in hydroponic chambers.
Btw....for full taste use glass pipes and bongs or pure hemp rolling papers.