Halle Berry -- I Got Proof Gabriel Bleached Nahla's Hair!

Halle Berry says she has the smoking follicle to prove Gabriel Aubry bleached and damaged her daughter's hair ... and the proof is in Nahla's hair brush.

TMZ broke the story ... Halle hauled Gabriel into court, claiming he was straightening and lightening her hair to make her appear white. Gabriel denied using chemicals and said the lightening was from the pool and sun.

Halle submitted documents to the court from Microtrace, a forensic consulting lab. Halle gave them a pink hair brush with strands of Nahla's hair.

The company analyzed the hair and concluded there was evidence it was chemically treated. The lab went on to say the repeated use of chemicals took their toll, writing there was "extensive damage ... likely the cumulative effect of repeated exposure to numerous gentle bleaching treatments."

The judge ruled neither Halle nor Gabriel could mess with Nahla's hair, and based on pics of Nahla and Gabriel from this week ... it looks like her hair is going back to normal.