Tanzanite is classified as a three-colored gemstone.
The highly prized deep-dark blue is hard to find in tanzanite under two carats.
Tanzanite is the most difficult gemstone to match. Jewelry requiring more than one stone can be a challenge.

When it comes to color, tanzanite is one of the trickiest gemstones to judge. Of course, the color of all gems shifts slightly under varied lighting conditions. But tanzanite not only changes color under different light, but it can also display several shades of color at once. Therefore it is important to examine tanzanite under many light sources so you know what shades to expect from a particular stone. After you determine the many tones, look at the stone again under a neutral-fluorescent light (which best mimics mid-daylight) to make the final judgment of the predominant hue.

So what is the ideal color for tanzanite? And how should you go about examining this chameleon of a gemstone? Here's a few pointers:

1. Since tanzanite began its career as a substitute for blue sapphire, and because blue is the most popular color for any gemstone, deep-dark blue is considered tanzanite's most desirable hue.
2. Keep your desired color range in mind when evaluating each stone. Some will emit purple and violet tones, others may tend more toward reddish or orange.
3. Think in terms of hue, tone and overall purity when examining any gemstone. Remember that tanzanite is classified as a three-colored gemstone, so determining the hue and purity can be tricky.
4. Examine the stone from the top, sides and bottom under each lighting source. The strongest color under all tests will be the hue of that particular stone, the most consistent secondary colors will determine the tone, and the lack of gray and brown will fix the purity.
5. It is important to note that the most valuable dark-blue color is hard to find in tanzanite under two carats.
6. Also remember that because of tanzanite's intrinsic trichroic (three-colored) nature, it is one of the most difficult gemstones to match. This becomes a bigger factor if you are considering tanzanite for earrings or other jewelry where more than one stone will be used.
7. If you are buying a stone with the intention of reselling at some point, you should try to find the deep-blue of highest quality. However, if you are looking for a tanzanite to match your eyes, wardrobe or skin tone, you can afford a little more freedom in your decision.

Answer to quiz: c