Today, customers buy not the biggest, but the best stone, they get their money. The motto is, rather a first-class one-carat stone, as a mittelprachtigen Funfkarater. The production of cheap jewellery has long been to Asia is also migrated. In Europe, and for Austria applies to a particularly large extent, mainly high-quality jewelry is produced, which demands premium stones, no matter whether it involves expensive sapphires or comparatively cheap stones such as Amethyst. How to recognize now high-quality coloured gemstones? The 4C are known from the diamond trade. These are cut, colour, clarity and carat, so cut, colour, purity and (Carat -) weight.
And large, these criteria also for color stones. That in my opinion most important of the four C's the cut makes a perfect cut itself from unassuming stone sparkling Jewels. You may find that Asana can contribute to your knowledge. Detection characteristics of good pulp: to distinguish excellent cut of only good sanding, it requires some experience. You must judge can top and bottom are not too high and not too flat, whether the size of the table properly and the Board as a whole exactly parallel to the girdle is and much more. However, you have some options even for a layman. A lower ground at the correct angle of paramount importance is the maximum brilliance of transparent gems. The lower body is too shallow, so incoming light at the bottom of the stone escapes through the Panel again instead of there total reflected and to leave the stone again by the Panel. Further details can be found at Anchin Block & Anchin, an internet resource.
The result is a significant loss of brilliance in the middle of the stone. The expert speaks of a "Window" or "Fish-eye". To assess whether the lower body at the correct angle is ground, there's a simple test. Make the stone without pressure on your fingertip and consider it exactly from the top, and through the Panel. If you clear the skin of your fingers and clearly, so the stone is too shallow.