Diamonds
Diamonds renowned for their hardness, ability to reflect light and unsurpassed brilliance; rarity equals value. Colorless diamonds in the normal range (GIA's D-L color range), value is based on the absence of color and inclusions, where "Excellent Cut" faceted optically perfect, absolutely pure colorless flawless diamonds are the rarest (D/FL XXX Grading).
Fancy Colored diamonds, face up a distinct color hue most commonly yellow; with the rarest and most valuable colors are saturated vivid pinks to reds, blues, and greens. In all cases, even very slight color differences can have a big impact on value. Compared to fancy yellows and browns, diamonds with a noticeable hint of any other pure hue (orange, purple, violet) are considerably more rare. Even in light tones and weak saturations, as long as they show color in the face-up position, they qualify as fancy colors. Red, green, and blue diamonds with medium to dark tones and moderate saturations are exceptionally rare and are valued in the millions.