Natural Iolite Ring Sterling Silver Filigree Setting. This pretty silver ring features a natural Iolite gemstone. Iolite is a semi-precious stone also known as a Water Sapphire. The correct color for an Iolite is an inky purple blue and this Iolite is the correct color. The ring measures 3/8 inches across. The Iolite is flush against the top of the setting. The Iolite weighs in at 1.25 carats. This ring is marked 925 and has been rhodium plated for exceptional shine. This sterling silver 925 filigree Iolite ring is in very good condition.