Terminator Librarian Paint Schemes
Space Marine Librarians weren't always blue! Paint schemes from the Genestealer expansion for the original Space Hulk board game.
Genestealer
Genestealer ↗ introduced psychic powers to Space Hulk. The box also had art painted on it detailing the rank markings of Space Marine Librarians.

Text from the image is reproduced below.
Ultramarines Epistolary
A Librarian's rank is indicated by the colours of the banding and gems on his Terminator Aegis suit, following colour schemes laid down in the Codex Imperialis. The silver banding and blue gems on this suit show the wearer is of Epistolary rank.
Space Wolves Codicier
This Librarian's Codicier rank is shown by bronze banding and green gems. He has also chosen to paint red and yellow checks on his storm bolter - this pattern is common amongst the Space Wolves, painted on various areas of their armour and weapons.
Blood Angels Lexicanian
Gun metal banding and black gems indicate Lexicanum rank. This librarian has chosen to personalise his Aegis suit by continuing the gun metal colour across his carapace and helmet. He's also painted the handle of his force axe red to symbolise the Chapter's rituals of blood-letting.
Dark Angels Chief Librarian
All the Librarians of he Deathwing have gold banding and red gems (usually the markings of a Chief Librarian). Deathwing Librarians add litanies of honour and purgation to all the plates of their armour; the scroll colour follows the normal Codex banding colours, so this Librarian's gold scrolls show he's a Chief Librarian.
Codex Imperialis Summary
| Rank | Banding | Gems |
|---|---|---|
| Epistolary | Silver | Blue |
| Codicier | Bronze | Green |
| Lexicanian | Gunmetal | Black |
| Chief Librarian | Gold | Red |