Larimar is a rare colored gemstone that is found in only one place: a mountainside on the south side of the Dominican Republic. Larimar has the appearance of turquoise, but its visual complexity and depth make it highly desirable. Because Larimar is a colored gemstone, a specific grading system by an accredited organization does not exist. However, some guidelines do exist to classify the gemstone. Seven classification characteristics are used to grade Larimar: color, pattern, luster, luminosity, clarity, translucence and chatoyancy. A stone perfect in all these would receive a grade of AAA, though this rating is overused and therefore ambiguous.

Look at the color of the gemstone. Color corresponds to the intensity and depth of the hue within a Larimar piece. The deeper and richer the color, the rarer and higher the grade of the gemstone. A deep cobalt, or volcanic blue, is the most sought-after Larimar color, followed by turquoise, sky blue, light blue and white. Plumes of red can be present on some Larimar pieces; this is formed by iron deposits, and these plumes are fairly rare. Green Larimar can also be found, but it is not as desirable as blue.

Examine the pattern present on the Larimar piece. Pattern corresponds to the design complexity of the stone. Look for multiple shades of blue or other colors on the gemstone. For instance, a deep blue stone with some white, green or red is intricate and rare. Elaborate and ornate patterns such as this will increase a Larimar stone’s value.

Inspect the degree of luster found on the Larimar gemstone. Luster has to do with light reflection from the surface of the gemstone. Larimar that reflects light and shimmers almost like a diamond has a high degree of luster, while a solid piece of Larimar that does not glisten more resembles a piece of turquoise without luster. Larimar that sparkles is more sought after than a stone that is dull.

Appraise the luminosity of the stone. A strong luminosity will give a Larimar stone almost an inner glow. This is similar to translucence but, unlike translucence, luminosity corresponds not only to a stone’s ability to let light pass through, but also its ability to capture and hold light.

Survey the clarity of the stone. Clarity corresponds to the purity of a Larimar gemstone. Any non-mineral material found within the gemstone will alter and decrease the clarity of the Larimar piece. Foreign objects, such as flecks, cast within the Larimar stone will reduce its worth. Defects such as cracks or pits within the stone will also diminish the clarity and value.

Observe the translucence of the gemstone. Translucence is the ability of the gemstone to allow light to pass through, the higher the translucence the better the grade. An opaque piece of Larimar will be a solid color, and will not allow any light to enter or pass through the stone. However, some Larimar stones have the translucence of emeralds or rubies, and these pieces are valued higher.

Inspect the chatoyancy of the Larimar gemstone. Chatoyancy usually has to do with the direction of the cut of the Larimar — whether the cut is parallel to or against the grain or fiber of the stone. A piece of Larimar with desirable chatoyancy will produce a surface reflectance similar to the shine of silk or a cat’s eye.