Wondering this- It's such a crucial component in the setting, but I don't know what it looks like. It's probably metallic, I guess. AP weaponry is usuallyt shown as red in the setting - is it possible it has a red appearance? Anyone who's read the rpg books have anymore info?
Most dense metals IRL do have a grey/silvery appearance, and similar mythological/fictional metals like Mythril and Adamantium are silvery-grey, so either to fit it's that, but since it's Phlebotinum and fictional, nothing stops it being another colour. Apparently there's a Japanese mythical metal that's red http://tvtropes.org/pmwiki/pmwiki.php/Main/Hihiirokane so maybe it's along those lines if it's not the more common grey shade most metals are. The RPG doesn't seem to have much about the colour of Teseum, sadly. If it's there, I'm not locating it.
Could be Iridescent like Iridium or Bismuth But I think I always pictured it as a silvery grey metal. Looking into it, apparently Controllers sheath Antipode claws in Teseum, and Mormaers have their armor lined with it so that might be our only actual references for color.
The Caledonian's Teseum claymores are also silver/grey. Though it's quite possible that various processing and/or alloying techniques change it's colour, giving rise to red, green, blue, and yellow blades depending on how exactly the material is treated.
Most (but not all) of the elements on the periodic table that are metals, other than gold, copper, and other reasonably recognizable metals are basically all described as Grey, Silver, or Lustrous with various tintings (often blue) when oxidized. I don't think it would be unreasonable to imagine Teseum being similar in nature to the high atomic number elements. (full disclosure I am not a chemist)
Id Guess the reason it may look red is not cause of the metal, but from a dye used to distinguish weapon types in the armory. Same could be applied to the bullets, don't want a line kazak with HMG to burn through AP ammo against infantry while some poor Tankhunter cant figure out why the Squalo isn't dropping.
Pinkest Pink pink! (On a related note, do look up the Blackest Black (which isn't the blackestest black, but is non-toxic and without exclusivity bullshit) if you want a really really dark model)
