how would you know wether a silk saree purchased by your mother is made from pre silk

WE CAN FIND OUT WETHER THE SILK SAREE IS MADE OF PURE SILK OR NOT BY BURNING A PIECE OF ITS FIBRE. IF IT BURNS WITH A SMELL OF BURNING HAIR AS HAIR AND SILK ARE MADE OF FIBROUS PROTEIN. THE  SILK SHOULD NOT MELT AND IT SHOULD PRODUCE A BLACK, HOLLOW IRREGULAR BEAD LIKE RESIDUE. IF THE ABOVE MENTIONED CONDITIONS APPLY THE SILK SAREE IS MADE OF PURE SILK.

HOPE IT HELPS!!!!
ALL THE BEST..
GRISHMA