It’s important to know that no standard quality grading scales exist for tanzanite – or any other colored stone. Diamonds are the only gemstone with a universally applied grading system. As a result, there is a bewildering array of terms used on the internet to describe tanzanite, most of which are entirely subjective and based on the author’s personal opinion, education, and commercial motives. This fact makes it very important for consumers to buy from a trusted source.