For Valentine's Day, instead of blending diamonds, Will it Blend? decided to blend, due to reasonable budget constraints, cubic zirconia. For comparison, they tell us where it lies on the Mohs scale. What they failed to mention is that the Mohs scale is just ordinal; all the numbers mean is what substances are harder and which are softer. The absolute hardness actually compares the differences in hardness.
Cubic zirconia have an absolute hardness of around 300, diamonds 1500. In terms of hardness, iron is to cubic zirconia as cubic zirconia are to diamonds.
To further complicate things, cubic zirconia are very brittle; impact from a softer object can easy cause fractures.
Now, I'm not going to try this with my normal blender; my blog doesn't generate enough traffic to pay for both the bling and the new blender, and I'm not even going to consider spending $400 on a Blentec blender.