Here is a 20.81Ct Large Rainbow of Color Opal. This is part of a jewelry store stock that will be auctioned this week. This large stone glistens with a rainbow of red, blue and green. If you collect gems or love to design your own jewelry- this would make a great center stone for a pendant or a one of a kind ring. Opal is the October birthstone. This 20.81Ct Opal will be auctioned to the highest bidder at $1 No Reserve.