http://wiki.spiralknights.com/Treasure_box
I don't know if Blue Treasure boxes exist, but the picture on the Wiki is a Red Treasure box that looks purple because of the blue lighting.
http://wiki.spiralknights.com/Treasure_box
I don't know if Blue Treasure boxes exist, but the picture on the Wiki is a Red Treasure box that looks purple because of the blue lighting.
That "Blue Box" appears to just be a Red Box under the lighting. I've seen no reports whatsoever of blue boxes outside of that one Wiki edit that put it there three days ago. It may or may not look less red and more blue depending on how the user's screen is calibrated. I'm going to revert this unless someone can come up with a blue box that isn't in a level with a blue hue overlay.
No. There are no blue treasure boxes.
It looks to me all the red boxes were simply changed to blue (perhaps to make them more distinct from the healing ones).