I just checked in-game, newest version, both on a modded and a pure instances.

The in-game fieldguide and the web-based are both wrong - or, the tier requirements are wrong in-code.

Fieldguide dictates that, Diamond, Ruby, Sapphire require black steel, Topaz, Emerald and Amethyst require steel - which are CORRECT.
The mismatched ones are: Lapis Lazuli stating wrought ironbut being mined with bronze, Opal - same deal as Lapis.