With all gemstones, clarity is the term which describes how free from flaws a given stone is. Flaws are identified in two categories. Internal flaws, called inclusions, and external flaws, or blemishes. Tanzanite is probably the most transparent, or "eye-clean" (free from visible flaws) of all fine gems. Because of this, the tolerance of visible flaws in tanzanite is greatly reduced compared to other gemstones.

There are many types of flaws inherent in tanzanite, most of which are harmless. The only thing you need to look out for are cracks which could greatly weaken the stone, or dark blotches that block light passage, hence clarity.

The same method of investigating tanzanite for color quality can be used to qualify its clarity: examining from multiple light sources and angles. You're looking for inclusions and blemishes which won't be visible from all angles. These flaws can have a detrimental effect on the stone's overall transparency and uniformity of color dispersion. Look from top, bottom and sides under overhead lighting, first with the naked eye, then through a 10X loupe. Next, examine the stone from all angles with light shining through the sides. Here's a couple more handy tips:

1. Always clean stones with a soft cloth before examination. Oil and dirt can block transparency.
2. Only compare tanzanite with other tanzanite, and only with the same quality, cut and size.
3. It's best to purchase any gemstone loose. Settings can hide flaws and make grading of clarity and transparency very difficult.

Answer to quiz: b