What means the blue fields in Alphabetty saga?

Sun-2

There are golden fields and blue / silver ones.Can't find anything about the blue ones

Randle

Hey Sun, the golden tile will double the value of the word it has been used for to link. The bluish (in fact silver) tile doubles the value of that letter that's on the silver tile. Hope this helps!

Randle

Hey Sun, the golden tile will double the value of the word it has been used for to link. The bluish (in fact silver) tile doubles the value of that letter that's on the silver tile. Hope this helps!

dnl2002

Hey Sun, the golden tile will double the value of the word it has been used for to link. The bluish (in fact silver) tile doubles the value of that letter that's on the silver tile. Hope this helps!

What about the occasional tile that has different color letters, not just background shade? I've seen blue and green font before, and have had long word creation leave green tiles behind (they look similar to the word suggestion green, but are static.)