Tanzanite Necklace Sapphire Or Tanzanite?

Sapphire or Tanzanite? - tanzanite necklace

I try to choose a necklace for my wife, especially a Helzberg. I can not decide between them so Tanzanite and Sapphire (very fond), which would be the jewel in the crown, with small diamonds. But ... During the search, I discovered that almost as Tanzanite is a relatively soft mineral. On the Mohs hardness scale that rates of 6 or 7, and sapphires of 9, second in the hardness of diamonds. I am sure it is a relative term, these gems are of course very difficult when compared to other substances, but as a light for me. I only know that the hardness resists chipping and scratching, so I asked if we could be someone on tanzanite, how sweet to enlighten. I mean, very well and will probably never be intelligent? Or is there a high probability that something will happen to the stone?

Please, no advice is better on the stone, because the money or anything ... Sapphires are obviously worth much more, but Tanzanite is much rarer than diamonds, and both have qualities of Nice, in particular color.