Ideal-cut diamonds have been carefully crafted to maximize light return over all other factors. Round diamonds in this group have the finest proportions, along with polish and symmetry ratings of either Very Good, Excellent, or Ideal.
A "near-colorless" grade diamond. Color is noticeable only when compared to diamonds of better grades. This diamond looks beautiful set in platinum or 18k gold, and offers an excellent value.
SI diamonds (which stands for "Slightly Included") have inclusions that can be seen fairly easily under 10x magnification. SI diamonds are the trickiest to purchase, since some SI diamonds are completely clean to the naked eye and others are not. Generally speaking, however, most SI diamonds will not contain any inclusions that can be located without using magnification.