What does a Colombian emerald cost?

People arrive expecting a price per carat, the way gold has a price per gram. Emerald does not work that way, and any store that quotes you a flat per-carat figure is simplifying something that cannot be simplified.

Color does most of the work

Color is the single largest factor, and it has three parts: hue (how green, and whether it leans yellow or blue), saturation (how intense), and tone (how light or dark). The stones that command the highest prices are vividly saturated in a medium tone. Too dark reads black at the edges; too light reads pale.

Between two stones of identical weight, color alone can produce a difference of several times the price.

Then transparency

Every emerald has inclusions. The question is whether they interrupt the light. A stone whose jardin is visible but whose body still glows is worth far more than one that looks cloudy, even if a loupe finds similar inclusions in both.

Weight, but not linearly

Large clean emeralds are genuinely rare, so price per carat rises as size rises. A three-carat stone is worth considerably more than three one-carat stones of the same quality, not the same.

Cut

The emerald cut exists because of this stone: the stepped corners reduce the stress on a brittle material and the long facets show color rather than sparkle. A well-proportioned cut brings the color to the surface. A cut chosen to save weight buries it.

Treatment

The multiplier nobody mentions. A significantly oiled stone can look like a lightly oiled one in a display case and cost a fraction. This is why the treatment belongs in writing on the certificate.

And then the setting

Metal weight, karat, workshop labor and any accompanying diamonds are a separate calculation altogether, and on many finished pieces the setting is a meaningful share of the total. Ask for the stone and the setting to be discussed separately. A seller who cannot break it down may not know.