AM modulation with colpitts oscillator ?

I want to generate an AM modulated signal with colpitts oscillator :

Colpitts Oscillator Calculator - Ekswai

can this be performed by connecting the audio signal (mic or whatever) between Rb2 and the ground ? if not then what is a good way to do AM modulation ?

thanx

It will work, but you will get also parasitic FM modulation (due to internal capacitance of the transistor which is part of the resonant circuit).
To get just AM modulation an easy way is to add a transistor buffer after the oscillator and modulate in amplitude its supply voltage using a transformer (or a transistor mounted as a regulator).

can i get an AM signal using a diode half wave rectifier followed by a filter ? or it's better to use a transistor ?

use a transistor..