What is iolite?
By Jared James · Last updated 21 May 2026
Definition
Iolite is a transparent to translucent gemstone cut from the mineral cordierite, ranging in colour from a soft violet to a rich blue-violet that can look remarkably like sapphire in certain lights. It has a pronounced optical property called pleochroism, meaning it shows different colours when viewed from different angles: from one direction it looks deep violet-blue, and from another it can appear almost colourless or honey yellow. The name iolite comes from the Greek word for violet, and it is sometimes called water sapphire for its colour.
Frequently asked questions
- Is iolite a good alternative to sapphire?
- Iolite offers a similar blue-violet colour at a much lower price, which makes it an appealing option for those who love the tone of sapphire but are working within a budget. It rates 7 to 7.5 on the Mohs scale, which is lower than sapphire at 9, so it is fine for pendants and earrings but needs a little more care in rings to avoid scratching.
- What does iolite symbolise?
- Iolite is associated with clarity of vision, guidance and inner truth. Viking navigators reportedly used thin slices of iolite as a polarising filter to locate the sun on overcast days, which has given it an enduring association with direction and clear thinking.
- What is pleochroism in iolite?
- Pleochroism means the stone shows different colours depending on the angle from which you view it. In iolite this is particularly strong: tilt it one way and you see deep blue-violet, shift the angle and it can look almost colourless or pale yellow. It is one of the most interesting optical properties in the gem world and part of what makes iolite distinctive.
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