Lab-created Ruby #5 (or Synthetic Corundum #5) is the classic, universally recognized industry standard code for “Burmese Pigeon Blood Red” synthetic ruby. Where Ruby #4 sits right on the boundary between dark pink and light red, Ruby #5 is a full, highly saturated, deep crimson red with a very subtle purplish undertone. It mimics the rarest, most prized color profile found in natural gemstones from Myanmar.