5 ms·

> They shine better [...] and nobody can tell the difference. I don't know much about gems, but this seems contradictory.

• Kadin 8y ago
  They appear to be a brighter cut than they actually are. To know the difference you would need to examine one closely. They're pretty much identical on casual inspection, especially mounted in a ring.
• kolpa 8y ago
  It means that you can't tell whether it's a "higher grade of Type A" or a "lower grade of type B", because both shine the same, and you can't tell the underlying purity of either nor the type of the stone you are looking at. Only if you know either the grade or the type (using high-tech instruments) can you infer the other from the observed shine.