Although turquoise is one of the more abundant gemstones, it has a following all its own. Of course, connoisseurs seek rare and extraordinary specimens. Before you make a major turquoise purchase, learn the nuances of turquoise buying.

Turquoise Buying and the Four Cs

The IGS turquoise value listing has price guidelines for turquoise cabochons.

Color

This copper mineral is famous for its blue hues, but shades of blue-green, green, and even yellowish green also occur. Ultimately, a bright blue with little green is the most highly valued color.

Green hues, arising from chromium or vanadium impurities, are less valuable but enjoy their own following. Turquoise with iron has yellow hues. While these hold less value, some artists seek out lime green turquoises for their projects.

If strontium is present, the stone can exhibit a rare secondary purple hue.

Ideally, color should be even and saturated with no visible color zoning. However, color zoning that creates a “bird’s eye” effect, with dark material surrounding light-colored nodules, is valued for its rarity. Arizona’s Turquoise Mountain mine once produced material with this quality.

Additionally, for the highest values, turquoise should have a medium-dark tone. Very dark stones appear dull and…