Presented here are two purple Whitall Tatum CD 154 insulators. The insulator on the left has a red tone to the glass. I have it next to a regular purple piece. They have the same color intensity but are clearly different. Many years ago there was a post on Icon where a collector was selling a similar piece and they called it dark grape. I do not know how common or uncommon these are but it is the first one I have come across.