This sapphire ring, offered by Etsy seller Atelier de Montplaisir, is quite the looker. The single stone weighs in at a hefty 23 carats, cut in a cabochon style. It is in an 18k yellow gold setting the seller dates to the mid-eighteenth or early nineteenth century, though it is not hallmarked. It is currently a size 4.75.
It can be yours for USD$25,000.