The price per carat should be less on diamonds with fair or poor polish. But most marcasite seen in jewelry is not marcasite, but pyrite (fool's gold); another brassy colored metallic mineral. It is sometimes called dichroite, and in its sapphire blue color is sometimes referred to as water sapphire or lynx sapphire.
Explanation of Cut, Color and Clarity of This Diamond
Cut Quality The ideal cut diamond is a very precise mathematical equation, where diamond proportions and angles are cut to optimize the diamond's superlative optical properties, in particular it's high refractive index and color dispersion, to create a diamond of unequaled beauty with perfect balance of brilliance and fire. In layman's terms, the diamond is cut to make it the most beautiful diamond so it retains its intrinsic value.
Color E color diamonds are virtually colorless. E color grade is very rare. The naked eye will not detect any presence of color. E color grade is indistinguishable from D without instrumentation.
Clarity Inclusions and external blemishes in diamonds of SI1 clarity may be easy to spot under 10X power magnification. Location of the inclusions greatly affect their visibility to the naked eye. SI1 diamonds of good color produce as good of a sparkle as the more expansive VS graded stones of lower color. Excellent bargains may be fond in this category.