Iolite VS Tanzanite – 4 Differences & 3 Similarities To Help You Decide

When it comes to blue gems we have a whole lot of options available. Most of the time the hues range form a deep sapphire blue to a sky blue to icy blue. Sometimes though, we see a bit of indigo, a bit of a purplish tint to the blue that makes it all the more interesting. Periwinkle and cornflower and sometimes even hyacinth blues are present and they are absolutely stunning.

Today we’re looking at the two main gems that achieve such colors, and those are iolite and tanzanite. We’ll compare the two, see their strong points, discuss price ranges and color ranges, and bring you all the information we can.

iolite tanzanite

Iolite vs tanzanite

Iolite is a bit darker, harder, and more affordable than tanzanite despite both gems showing impressive blue-purple colors. It’s far easier to find tanzanite at a jeweler or retailer than it is to find iolite, and this can matter a lot when deciding which gem to use for your jewelry. Both gems show pleochroism when viewed from different angles, but the number of the colors change, as dot he colors themselves.

What is iolite ?

Iolite is a type of cordierite, a silicate compound. It owes its blue-purple hue to trace amounts of magnesium (red), iron (yellow), and aluminum (blue). It’s not a very well known gem, as far as gemstones go, but still beautiful.

What is tanzanite ?

Tanzanite is the commercial name for the blue-purple version of zoisite. Tanzanite owes its blue tones to trace amounts of vanadium. This gemstone is quite popular and easy to find at a jeweler and retailer.

Read also: What Gemstones Are Blue ? 

1. Iolite is a harder gemstone than tanzanite

Iolite is a harder gemstone than tanzanite, meaning it will not scratch as easily as tanzanite would. For jewelry, especially pieces you intend to wear every day, this matters a whole lot.

Iolite scores a 7-7.5 out of 10 on the Mohs scale, while tanzanite scores a 6.5 which makes it a bit more prone to scratches and chipping. For pieces like engagement rings and bracelets that you wear every day, this can make a bit difference.

2. Tanzanite comes in a lighter indigo-purple hue than iolite

The color family of tanzanite and iolite is pretty much the same (blue-violet) but they show these colors differently. Tanzanite tends to show a bright, vivid blue with purple tones. Think a slightly less saturated hyacinth or bluebell. Sometimes a vivid color tanzanite can go into lavender territory. Even the lighter toned tanzanite still shows good color.

Iolite on the other hand is a bit darker, a bit muddled when compared to tanzanite. Iolite may remind you of ink spilled into a glass of water, it’s a darker color but not as saturated as tanzanite. A beautiful color on its own, but this gem can show a lot of dark spots if not very well cut.

Here’s an example of the typical color a vivid tanzanite will show. This tanzanite necklace off Amazon is a simple yet elegant design that will go with pretty much anything.

The center stone for the pendant is a round-cut tanzanite, surrounded by a halo of small white diamonds. The metal for this necklace is 14k white gold. Simple, elegant, and definitely something to be cherished if given as a gift.

3. Iolite is far cheaper than tanzanite

Iolite sells for far less than tanzanite, and this can make it a very affordable gem if you’re looking for something for a cocktail ring, or simply gemstones for fine costume jewelry. You can find iolite for about $13 per carat for a gem with good clarity, medium saturation and medium-dark tone. Lighter color iolite sells for less.

Tanzanite sells for an average of $500 per carat for a vivid color gemstone with great clarity. Tanzanite with many inclusions or semi-opaque ones sell for the lowest price, about $5 per carat.

4. Tanzanite is better known and easier to find at a jeweler’s

If you’re looking for ready-made jewelry you have more of a chance with tanzanite jewelry. This gem is far better known by the public and thus in higher demand than iolite. Jewelers will definitely carry tanzanite, but retailers will almost always have a few pieces that are already set in some for of jewelry or another.

Iolite may be harder to source, and far more difficult to find if you’re looking for a ready-made piece. Jewelers might not have it on-hand but they can definitely source one for you.

Here’s a necklace with iolite and diamond off Amazon to give you a rough idea of what you can expect for pre-made iolite jewelry.

This necklace features three stones, with the center one an iolite with an emerald cut, and the side stones slightly smaller diamonds with emerald cuts as well. The three stones are set in a half bezel, in 14k white gold.

Similarities between tanzanite and iolite

These were all the key differences between tanzanite and iolite, but these gems do have quite a few similarities between them. We should take a look at these too, so make sure we  truly understand both gems.

1. Both tanzanite and iolite show pleochroism

This is something others might class as a difference, but we are listing it as a similarity. Both tanzanite and iolite will show you a completely different color if you view them from a different angle. This is called pleochroism, and it simply means that a gem can chow more than one (pleo- many) colors (chroism- color range) when you turn it in your hand.

This is not the same as color change, where the gem changes color depending on the type of light (incandescent vs cold).

Tanzanite shows three different colors – blue, purple, and burgundy – depending on what axis you view it from. Here’s a Youtube video show you that. Iolite generally show blue to light yellow, depending on the viewing axis, so here is a Youtube video showing you the color change.

This color change is most apparent when the gems are in their rough form. A lapidary’s job is to faced and orient the rough gemstone so the best parts are visible. In this case, the blue axis. So a very well cut tanzanite or iolite will show you its blue side. When turned to the side it might show a bit of the other colors.

2. Both tanzanite and iolite are good sapphire substitutes

Tanzanite and iolite are both really beautiful blue-purple gems that can easily be confused for fine sapphires, in terms of color only. Tanzanite is the more believable one, but a good iolite can fool most people at first glance. So if you’re looking for gemstones to substitute a sapphire with, for whatever reason, both tanzanite and iolite will work, with tanzanite a bit more believable.

3. Both tanzanite and iolite are indigo gemstones

Iolite and tanzanite show roughly the same colors. One goes a bit darker and less saturated while the other goes a bit more vivid. If you’re not very keen on details you could say they’re the same gem but in slightly different colors, the same way an emerald can be lighter or darker.

So, you could easily use one gem in place of the other, or to be specific you could use a very well colored iolite in place of tanzanite if the situation requires it. Examples include set costumes where the camera doesn’t zoon in too much for detail. cocktail rings or big statement necklaces, or simply dupes of the real thing when you’re traveling and don’t want to lose something precious.

Interesting facts about tanzanite and iolite

There are a few more tings to discuss for tanzanite and iolite, and those are some interesting facts that may tip the balance in the favor of one gem or the other, depending on what you like best. So let’s take a look.

Tanzanite is a December birthstone

If you’re born in December or have strong ties to the month of December (first child, anniversary, wedding, etc) then tanzanite may be a better fit for you as it’s one of the December birthstones. This is part of the reason you’re bound to find tanzanite much easier than iolite.

Iolite was possibly the Viking sunstone

Have you heard of the Viking stone ? Back when Vikings roamed the seas (and lands) they had to brave treacherous weather. An din the long sea journeys landmarks were difficult to com by, so they have to navigate using the sun, stars and the moon. But, often the skies were cloudy and stormy, and there was no way to tell the direction of the sun by looking at the clouds.

So the Vikings were clever and used a large slab of transparent rock that they called sunstone. It changed color depending on where the sun was, so they could easily move the slab around to guesstimate the position of the sun, and through that adjust their course.

How did it work ? Historians believe the slab in question was a big chunk of iolite, which changed from purple-blue to light yellow when exposed to filtered light (the clouds).

Tanzanite was named so by Tiffany&Co.

Tanzanite may have sounded very familiar when you first heard about it. Want to know why ? Its commercial name is inspired right from the country Tanzania, where the biggest deposit was found. This was a brilliant marketing move by Tiffany&co. when this gem first hit the market. The original name was purple zoisite, which didn’t sound as exotic, recognizable, or just that interesting.

Tanzanite ? Well, come and see this beautiful blue-purple gem from the exotic land of Tanzania, from the very heart of Africa ! Doesn’t that sound more interesting ?