Here is a 6.98Ct Australian Boulder Opal. This is part of a Jewelry store stock that will be auctioned this week. This has some pretty patterns of Blue and Green. If you collect colored stones or love to design your own jewelry- you won't want to miss this auction. Opal is the October birthstone. This 6.98Ct Boulder Opal will be auctioned to the highest bidder at $1 No Reserve.