Estate Natural Iolite Ring Sterling Silver Filigree. The Iolite is 1.25 carats. US Ladies Size 6.75. This pretty silver ring features a natural Iolite gemstone, 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. This ring is marked 925 and has been rhodium plated for exceptional shine. This sterling silver filigree Iolite ring is in very good condition.