How to Value Aquamarine

Identifying an Aquamarine

• 1

  Examine the stone's color under natural light. While less expensive blue topaz superficially resembles aquamarine, it lacks any trace of the greenish hue that distinguishes genuine aquamarine.

• 2

  Test the stone with the diamond tester. Jewelers use this device to measure a stone's thermal conductivity; if the stone registers, it is most likely blue topaz, not aquamarine. Conduct a less precise test by holding the stone between your palms for a minute; genuine aquamarine conducts heat poorly and won't warm significantly from body heat.

• 3

  Examine the stone for nicks and scratches. Aquamarine has a hardness of 7.5 to 8 on the Mohs scale, while glass is a softer 6 on the scale. Use the jeweler's loupe to get a better view at ten times magnification. If the stone bears scratches, it's probably tinted glass and not aquamarine.

Evaluating the Aquamarine

• 4

  Note the stone's shape. Popular gem shapes such as round, oval, marquise, emerald and pear are standard, but unusual cuts such as Asscher and cushion shapes can fetch a higher price. Very large display gems for collectors can have virtually any shape, but the best cuts are those that follow the crystal's natural lines.

• 5

  Look at the loose gem against white paper. The richer the color, the more costly the stone. The costliest aquamarines resemble the sea along a tropical white-sand beach.

• 6

  Examine the stone's clarity both with the naked eye and with the jeweler's loupe. Aquamarines are typically clear to the unaided eye; a stone with visible inclusions or flaws loses value. If the aquamarine has inclusions visible only with the loupe, its cost is less affected.

• 7

  Weigh the stone on the jewelry scale. The aquamarine's cut, color and clarity set its price per carat; its weight in carats determines the gem's final value.