I love Tanzanite. Cheaper ones are very light in colour, but the most expensive ones (which I will never be able to afford) are a deep violet blue. Tanzanites are one of very few trichroic (having three layers of colour) gems. Tanzanites differ in shade (and look different under different lighting conditions) but most of them shift violet, blue-violet, indigo, violet-blue, or blue. Most Tanzanites are natural, but heat-treated. Many of them are heated in the ground so have flashes of blue, but they do need to be heated to get those saturated gorgeous shades.
Here is a tanzanite before treatment
And here is afterwards
Find the entire article by Antony Zagoritis and the original photos here
