How much a diamond cost per Karat?

Answer 1

The myriad of other characteristics of diamonds (clarity, color, cut, polish, shape) it all becomes very subjective.

But if all things are equal, the scale is sliding. For example, a 1.5 caret diamond is more more rare than a .5 carry diamond so a 1.5 would command much more than three times the cost of a .5 (more than 10x in fact). To give you some sense, a .5 may cost $1,500, while a 1.5 may cost $15,000+.