In other words, they want the light to reflect back through the top, rather than out the sides or directly through the bottom of the diamond. For a perfect fit get this printable ring sizer on top of the following page & mesure the finger. Although the ring shows a commitment to the person, the actual historical reasons for an engagement ring are a little less obvious.
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 K color diamonds have faint yellow color. Mounted in yellow gold, they look dazzling. Look for diamonds in this color range with medium to very strong fluorescence to minimize yellowish color effects. Choosing K color diamond allows to go for a bigger size and more extravagant look.
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.