  Dust grains are the building {blocks} of future planets. They evolve in size,
shape and composition during the life cycle of the interstellar medium. We seek
to understand the process which leads from diffuse medium grains to dust grains
in the vicinity of protostars inside disks. As a first step, we propose to
characterize the dust evolution inside pre-stellar cores thanks to
multi-wavelength observations. We will present how NIKA2 maps are crucial to
better constrain dust properties and {we will} introduce SIGMA: a new flexible
dust model in open access.
