Questions about Sorcerer's Stone

[india jones]

No: HPFGUIDX 146621

In Sorcerer's Stone it says that the Bloody Barons' robes 
are spotted w/ silver blood, I was wondering is this unicorn blood or 
does the blood simply appear that color because he is a ghost? Sir 
Nick is shown in color and I am wondering why the blood appears silver 
and not some kind of red? And the goblin uniforms at Gringott's are 
scarlet and gold, is there a connection between them and Gryffindor?
Nikki