Lost Tales version: After we get a detailed description of Noldor gem making (what materials they use, etc), we get to the making of the silmarils:
Then arose Fëanor of the Noldoli and fared to the Solosimpi [Teleri] and begged a great pearl, and he got moreover an urn full of the most luminous phosphor-light gathered of foam in dark places, and with these he came home, and he took all the other gems and did gather their glint by the light of white lamps and silver candles, and he took the sheen of pearls and the faint half-colours of opals, and he ?bathed them in phosphorescence and the radiant dew of Silpion [Telperion], and but a single tiny drop of the light of Laurelin did he let fall therein, and giving all those magic lights a body to dwell in of such perfect glass as he alone could make nor even Aulë compass, so great was the slender dexterity of the fingers of Fëanor, he made a jewel, and it shone of its own...............radiance in the uttermost dark; and he set it therein and sat a very long while and gazed at its beauty. Then he made two more, and had no more stuffs, and fetched the others to behold his handiwork, and they were utterly amazed, and those jewels he called the Silmarilli....
It is, generally, a very good thing that Tolkien moved away from this level of detailed description of magical events to much more 'and then magic happened!' later. We will have to show something, but probably not this. I merely put it here as a reminder of Tolkien's very early conception of what 'making the silmarils' looked like.