Why get caught in the weight trap?

When selling an expression of love, why focus on the least important factor that could be misleading?  Non Ideal Cut diamonds with thick girdles (and steep crowns, deep pavilions) "steal" the diameter that should be there for the size, and reduce the overall beauty.  An incorrectly cut 1.25 ct. could have the same diameter as a 1 carat Ideal, and t...