The Moon now shone upon the grey face of the rock; but they could see nothing else for a while. Then slowly on the surface, where the wizard's hands had passed, faint lines appeared, like slender veins of silver running in the stone. At first they were no more than pale gossamer-threads, so fine that they only twinkled fitfully where the Moon caught them, but steadily they grew broader and clearer, until their design could be guessed.
At the top, as high as Gandalf could reach, was an arch of interlacing letters in an Elvish character. Below, though the threads were in places blurred or broken, the outline could be seen of an anvil and a hammer surmounted by a crown with seven stars. Beneath these again were two trees, each bearing crescent moons. More clearly than all else there shone forth in the middle of the door a single star with many rays.
'There are the emblems of Durin!' cried Gimli.
'And there is the Tree of the High Elves!' said Legolas.
'And the Star of the House of Feanor,' said Gandalf. 'They are wrought of ithildin that mirrors only starlight and moonlight, and sleeps until it is touched by one who speaks words now long forgotten in Middle-earth. It is long since I heard them, and I thought deeply before I could recall them to my mind.'
'What does the writing say?' asked Frodo, who was trying to decipher the inscription on the arch. 'I thought I knew the elf-letters but I cannot read these.'
'The words are in the elven-tongue of the West of Middle-earth in the Elder Days,' answered Gandalf. 'But they do not say anything of importance to us. They say only: The Doors of Durin, Lord of Moria. Speak, friend, and enter. And underneath small and faint is written: I, Narvi, made them. Celebrimbor of Hollin drew these signs. '
My picture take on it