Although named demantoid, or “diamond-like,” these garnets actually exceed diamonds in both brilliance and dispersion. Their horsetail inclusions are a delight to collectors, too.

Before you go demantoid garnet buying, learn about the quality factors that impact cost and find out what makes this variety of the January birthstone unique.

Demantoid Garnet Buying and the Four Cs

The IGS garnet value listing has price guidelines for demantoid garnet. Learn to identify the different species of garnet.

Color

Demantoid is the green variety of andradite garnet, with colors ranging from deep forest greens to light, nearly colorless hues. For this variety, the connoisseur’s most important consideration is the trade-off between depth of color and visible brilliance.

While demantoid has a higher dispersion than diamond, darker tones may obscure this effect. Still, medium-dark tones hold the highest value, where the green color is strongest. For those who prefer greater dispersion, a slightly lighter gem will sparkle strongly without much loss of color.

Yellow secondary hues are often present and detract from the gem’s price. Gems with low saturation will appear more brown.

Clarity

Although high clarity is always desirable, some connoisseurs and mineral enthusiasts will delight in the horsetails…