Here is a 1.20Ct Opal. This is part of a Jewelry Store stock that will be auctioned this week. Opal is the October birthstone. If you collect colored stones or love to make your own jewelry- you won't want to miss this colorful stone. Opal is the October birthstone. This 1.20Ct Opal will be auctioned to the highest bidder at $1 No Reserve.