I got a set of centennial coins from Canada today. The "animal" sides were facing outwards and all the silver pieces were toned a blue color. When I got it home looked at the obverses and found some rather strange toning...it's kind of speckled in orange, reds, and blues. Because of the variety of ways that these were packaged by the mint, banks, and other private concerns, I'd imagine that there are a lot of different toning types and colors available.

The dark blue/violet is probably the most common color, and often shows on one, though also both sides as well.

The Bank of Montreal holders offer among the most interesting toned pieces.

The back almost makes it look like it was still proof before it toned/oxidized.