An Emerald stone that does not shine, not transparent from the center of the gemstone, or is light in color, is not a fine gemstone. If an Emerald is too dark, then it is considered as a fine quality Emerald.
Emerald gemstone belongs to Beryl family and is of beautiful velvety green color. Being a colorless in it’s purest form, Beryl enrich with chromium and vanadium gives this flawed but fab gemstone a rich color. By flaws, we all mean crack or smudge notably black. It is considered to be that flawless Emeralds are very rare and are quite costly.