CUT DESIGN OF DIAMONDS PROVIDING PLENTY OF VISUAL-PERCEPTIBLE REFLECTION FOR ORNAMENTAL USE AND OBSERVATION METHOD THEREOF

摘要

A cut design of an ornamental diamond and an observation method of the diamond which an observer can perceive a more beauty, are disclosed. The cut design is a round brilliant cut comprising a girdle, a crown above the girdle and a pavilion below the girdle. A girdle height (h) is 0.026 to 0.3 times a girdle radius, a pavilion angle (p) of a pavilion main facet ranges from 37.5 degrees to 41 degrees, and a crown angle (c) of a crown main facet is within a range of satisfying: c-2.8667xp+134.233 and p1/4x{(sin.1(1/n)+sin.1(1/n.sinc))x180/.pi.+180-2c}, wherein n: refraction index of a diamond, .pi.: circular constant, p: pavilion angle in degrees, and c: crown angle in degrees. The cut design of the ornamental diamond provides an observer with plenty of visual- perceptible reflection when the observer watches the diamond above a table facet with a sight line of an angle less than 20 degrees with a vertical line at the center of the table facet.