Fellows Auctions has a heaping handful of beautiful natural blue sapphire rings hitting the auction block this week for their May 15th Antique and Modern Fine Jewelry Auction. Their origins vary and so do their treatments, making some much more expensive than others. My absolute favorite is the first listed below, which is a natural sapphire originating from Sri Lanka set with a large gold halo accented with old cut diamonds. Click through each photo to go to the auction listings. Can you guess which sapphire is treated and which is not?