When anything is popular, it tends to be imitated and that goes for Lapis Lazuli as well.  Key characteristics need to be present in order to authenticate it as being real and of value as a semi-precious stone.

• Lapis Lazuli is a rock.  It is opaque although depending on the cut and the thickness can at times appear translucent.
• Lapis Lazuli has a deep blue color and almost always has pyrite inclusions. Remember pyrite is gold in color. These should be small – more like grouped flecks.
• There should be no streaks of white which is calcite. Note that some producers dye the stones, including the white streaks to enhance the color. These stones are usually very dark blue and have a gray cast to them.
• The stone should have no fractures in it.