Tanzanite vs Sapphire

Hi, I'm Steve Moriarty from MoreGems.com and today we're discussing sapphire versus tanzanite. I'm going to give you a little information about what they're made of, what the colors are like, their hardness, their durability, how they're treated, and what cleaning methods you can use on them, as well as on the end I'm going to give you some price comparisons.

So our first example is a blue sapphire, this comes from Sri Lanka. And I have a sapphire crystal. So the sapphire crystal's in the hexagonal system and it is composed of aluminum oxide.

And our other example is a tanzanite. Both of these are just under 6 carats. And here is a tanzanite crystal. This crystallizes in the orthorhombic system and it is a calcium aluminum silicate.

So when it comes to color, both these stones do exhibit both blue and violet, with the tanzanite of course having much more violet and the sapphire being much more blue, but they both have the ability to mimic each other. Occasionally tanzanite comes in a almost pure blue color, much like a sapphire, but that's rare. And also occasionally you see sapphire with a lot more purple. I mean, we'll see that from particular sources will produce more purple color, and you also get stones that are color changing, in sapphire, from blue to purple, which is a characteristic that tanzanite also exhibits when you go to different lights, it'll be more blue in daylight and more violet in incandescent lighting. So they have a similar color range, but the typical colors with sapphire being more blue and typically tanzanite being more violet.

So one source with a notable tendency towards violet is the Kashmir sapphire. And one other thing we've noted, on one of our trips to Montana, that is similarity between sapphire and tanzanite, is red flash. We talk about red flash in tanzanite, but I had never known that existed in sapphire until we looked at about a carat and a half Yogo sapphire and, like tanzanite, it exhibited that red flash and I've never seen this noted anywhere, but it was notable.

Gemologically, one of the biggest differences between sapphire and tanzanite is, of course, hardness. Tanzanite has a hardness of six and a half to seven while sapphire is nine in hardness. So wearability of sapphire in a ring is greater. So that is one of the benefits of sapphire.

When it comes to brilliance, they are very similar because the refractive indexes are similar. Tanzanite has a refractive index of right under 1.70, with sapphire being 1.76, which is really not enough difference to make a significant difference in the brilliance. Brilliance is more affected by depth of color. So sometimes sapphire is overly dark and that has a negative effect on the brilliance of the stone, whereas tanzanite generally is never overly dark, so the brilliance is pretty much unaffected by that factor.

Next would be the clarity of the stones, with tanzanite being generally very clean and sapphire generally always having some inclusions.

Specific gravity would also be a characteristic that has an effect on the look of tanzanite versus sapphire. The specific gravity of tanzanite is 3.35 while sapphire is 4. And what that does, the specific gravity is the density of the stone, so when we compare two stones of equivalent size, the tanzanite, if they're cut similarly, will appear bigger because of the lower specific gravity. So for a given weight you get a larger looking stone in a tanzanite.

Both tanzanite and sapphire are typically heated. Now, here we have a tanzanite crystal that's unheated and you could cut a stone out of this and it would be blue, but typically they're much more brown and require heat treatment to get the blue color. This is a sapphire crystal, also unheated. Quite often these grayish looking stones, in Sri Lanka called Geuda, can be heated and turned blue. So heat treatment is an important process in these stones. In the case of sapphire, an unheated sapphire can be 30% more valuable than the heated stone. In tanzanite, we don't generally have a difference in the pricing, partly because we can't identify whether a tanzanite is treated or not. But probably 99% of all tanzanites are heated. And it may be a similar number, it's probably less than that now just because the value of sapphire has increased so much for being untreated that there is a push to sell untreated stone. But to get the true beauty of both these stones, they generally require heat treatment.

In regards to cleaning these two stones, in the case of sapphire pretty much all the methods that a jewelry shop uses, including ultrasonic and steam, are no problem. In the case of tanzanite, although not recommended, we have used ultrasonic for years. You don't want any sudden heat shock because of when you run the ultrasonic for a long time it gets very hot. That's not good for tanzanite, but we found that the ultrasonic has been safe. Steam, you never want to use steam. Steam will destroy this stone.

As a price comparison here's two stones of equivalent size, just under 6 carat, tanzanite and a sapphire. The tanzanite is $3,500 and the sapphire is $35,000. I've done some research with the Gem Guide, which is a market-driven pricing guide. And to compare the prices, a 1 carat sapphire is five times what a 1 carat tanzanite is. A 2 carat is six times the price, and a 3 carat is six and a half times the price when comparing sapphire and tanzanite. And 5 carat were 9.2 times the price of a tanzanite to buy a sapphire. And when you get to 10 carat it's almost 11 times. So tanzanite has a huge benefit price-wise for a similar beauty.

So both these gems, sapphire and tanzanite, beautiful gems worthy of owning. And you can find tanzanite on Tanzanite Jewelry Designs, and sapphires on MoreGems.com. So I want to thank you for watching. Don't forget to subscribe and like to see future educational videos.