The Crimson Carapace Shield looks exactly the same as the Crude Shield and the Runic Shield. It is special in such as it is only available from Collectors and cannot be found as loot from monsters.
When people refer to this shield, they are often talking about the collectors' shields from Yorik or Hagnon Warblade or Lord Dorn Lendrigen which are very popular for their inherent stance bonuses.
Despite its name, the default color is yellow/gold - although Tarnen's Shield, which uses this skin, is actually colored crimson.
