They are all lab grown. The difference is in their chemical structure and their refractive indexes (sparkle).
Lab diamonds (Fire Light) and Moissanite are graded just like natural diamonds. Cubic zirconia is not graded and that includes Diamonique and Radiance by Absolute.
Natural diamonds contain trace amounts of nitrogen. Lab diamonds do not and that can be tested to determine their origin...lab or natural.
I like charts. Here's one that you may find helpful:
(they misspelled zirconia)
