How we score gemstones
The AltGems Score is our way of rating every stone on the same honest scale, so you can compare a diamond, an amethyst, and an opal at a glance. Each stone gets a 0 to 10 score on five dimensions, calculated from objective data, not opinion. Here is exactly what goes into it.
The five dimensions
Durability
How well the stone resists scratches, based on its Mohs hardness. Higher Mohs means a higher score.
Brilliance
How much light and sparkle the stone returns, based on its optical class (dispersion and refractive index). Faceted, high-RI stones score highest; opaque stones score for color rather than fire.
Value
How much beauty you get per dollar. More affordable stones score higher here, so a high score means accessible, not low quality.
Rarity
How scarce and collectible the stone is, based on its market price ceiling and known rarity. Lab-created stones score low because they are abundant.
Everyday wear
How suitable the stone is for daily-wear jewelry, combining hardness with a penalty for stones prone to chipping or cleavage.
Why we built it
Retailers sell stones but rarely compare them neutrally, and crystal sites cover meaning without the buyer data. The AltGems Score bridges both: a single, transparent rating you can trust, applied identically to all 112 stones in our database. Scores update as our data does.