The transparent form of the mineral Cordierite is referred to as Iolite in Gemmology. This stone is found scattered among the igneous rocks and is never manufactured synthetically. Even though Iolite resembles Sapphire and Tanzanite and is also called water Sapphire, the same is distinguished from the other two by its optical property of pleochroism, i.e. displaying the colours of violet-blue, pale-blue and pale yellow when the light is transmitted through it from different directions. Sapphire and heated Tanzanite are dichroic, i.e. they display only two colours when light is passed. The pleochroism had once enabled it to function as the compass for sailors in cloudy days during a time when the compass was not invented.

The 4Cs namely cut, colour, clarity, and carat weight help in determining the quality of the stone. The prices of the stone go up to the value of expensive Sapphires and Tanzanite as the blue colour deepens, and the colourless ones are inexpensive. The perfect cut exposes the deep blue colour making the other two-component colours of pleochroism indistinct.

Square, round, oval and cushion are the traditional shapes in which the stone is cut. Due to the brittle nature and distinctive cleavage of Iolite, it is prone to breakage if not cut properly. Since the stone is transparent, the clarity also should be taken care of, as the inclusions if any, will be visible. Iolites are found in medium sizes ranging from one to ten carats, and 1-5 carat weight stones are widely used in jewellery due to their affordable price.

In jewellery, they go well with precious metals like Gold, Silver and Platinum and also with cheap metals like Copper and Brass. When they are used along with white gold and Platinum, the dazzle of the stone looks more pronounced in the white background. The Iolite stone is utilised in the making of rings, pendants, bracelets and necklaces. Precious stones, namely Amethyst, Peridot, Topaz, Quartz, Amber and Diamonds find their perfect partner in Iolite. Most people prefer engagement ring embedded with Iolite as it imparts the perfect blue colour to the ring, which symbolises the depth and value of the relationship. Moreover, it is affordable compared to Sapphire and Tanzanite.

The Iolite stone has many beliefs connected to it and is said to have physical and emotional healing powers. It is believed to keep the nerves stronger, troubled minds soother and also to help us achieve our goals and dreams.