  Inside carbonaceous chondrite meteorites are tiny dust particles which, when
heated, release noble gases with an isotopic composition different from what is
found anywhere else in the solar system. For this reason it is believed that
these grains are (inter)stellar dust which survived the collapse of the
interstellar cloud that became the solar system. We will describe here why we
believe that the most abundant of these grains, nano-diamonds, were formed in
the atmospheres of carbon stars, and explain how this theory can be tested
observationally.
