At the mere sight, it is not easy to recognize a good black melanosporum truffle. Therefore, when you want to buy a truffle on a stall, I recommend you to check the following criteria:
1) Aroma - When you smell the truffle, it should give off pleasant aromas.
2) Firmness - the truffle should feel firm to the touch.
3) Colour - Its flesh must be black with white veins (check at the location of the canifage: cut with a knife so that the flesh can be seen).