December Birthstones: Is Tanzanite a Good Buy?

As most of you who read my blog know, I don’t think much of birthstones.  My own birthstone is pearl, with alternates of moonstone and alexandrite, but my favorite gems are emerald, sapphire and tsavorite.  All of these go well with my skin tone and with the colors I like to wear, which should really be more important.

While the association between zodiac signs and specific gems goes way back, the list of birthstones was standardized some time in the last century by the Association of Jewelers in America.  That list only bears a passing resemblance to the zodiac birthstones and the various other birthstone lists that are floating around.  And since Tanzanite was only discovered in 1967, it wasn’t on any of the old lists anyway.  It was only recently added to the December birthstones - for marketing purposes.

Melted Tanzanite Ring - SOLD

When first discovered, Tanzanite, which belongs in the zoisite family, was dirt cheap.  Nobody knew about it, so there was no market for it.  An old time jeweler told me once that he was given Tanzanite for next to nothing in the early 1970s.  Other dealers have told me the same. 

These days, the Tanzanian government controls production, and since Tanzania is one of the poorest countries in the world, I am assuming that the Tanzanian people profit very little from this.  Prices have risen significantly since the early days.  Tanzania is the only country in which Tanzanite is found, and there are only 4 mines or so in which it is produced.  Serious flooding issues have created difficulties for mining, so it isn’t clear how much Tanzanite is actually available.  Lastly, there’s a government ban in place which prohibits any Tanzanite to be shipped to Jaipur for cutting (many, if not most of the worlds gemstones are cut in Jaipur).

All these factors make it tough to judge if Tanzanite has any true collector’s value.  And there’s one more issue – the most serious one to me.  Tanzanite is a very soft stone.  It can crack during setting – this has happened to me more than once.  If you have it set in a ring, don’t wear it every day, and take it off before doing any chores.  My stone dealer D., who carries very little Tanzanite, which dates to the early mining dates, is no longer buying any more.  His materials consist of smaller, lighter, stones which show no evidence of heat treatment.  His reason for not trading in it is that often, jewelers will borrow a stone to show it to a customer, but they will put it in a mounting first (so it looks really nice).  If the customer turns down the stone, it may come back to D. scratched or cracked.  If D. does not carefully re-inspect his merchandize, he may not notice and then no reclamation is possible.  Or the jeweler will simply claim that he didn’t crack the stone, and these sort of disputes are hard to settle.

Tanzanites are pretty much universally heat treated.  During the earlier mining days, some deposits found on the surface, where they were exposed to sunlight (which provides natural irradiation), were naturally light purple.  Ordinarily, however, the material that comes out of the ground is brownish, and has to be heated to drive bring out the purple.

In terms of color, the most desirable Tanzanite has a rich dark bluish purple.  Lighter stones, the lavender colored ones, are less valuable.  In smaller sizes, however, that may be all that’s available because the depth of a stone is what creates the darker color.  If you re-cut a stone that has a rich dark coloring, you may surrender some of its color intensity.

My evaluation?  Tanzanite is a beautiful stone, you should buy if it you love it.  But if you are a collector, there are better investments out there.

My last pair of round Tanzanite Post Earrings