is known for its "zoning". It may have areas of dark purple
surrounded by lighter purple or even colorless quartz. With careful
cutting, orienting the color in the culet, the gem will be evenly
colored face up. This brings the gem to its highest beauty and eye
appeal. If you can see the zoning face up, or with just slight tipping,
it reduces the value of the gem.
also common in sapphire. The same principle applies, if you can't
see the zoning face up; it has no effect on the value of the gem.
to be looking directly on to the plane of color to distinguish the
banding. Due to the cutting, the banding will only be visible in one
facet at a time. It takes a bit of practice to see this, but it is
So you see how much information you can get from a loupe. If you are a beginner, this will probably bring up dozens of new questions and they will direct you to your next level of study.