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How to Identify the Crystal Shape of an Aquamarine

Aquamarine, Latin for "water of the sea," is a gemstone-quality variety from the beryl family of minerals (translucent glassy minerals) that is closely related to the emerald. Named as the birthstone for the month of March, aquamarine varies in shade from an almost colorless, clear blue to a slightly deeper shade of blue or blue-green. Usually it is a transparent gemstone but occasionally exhibits the appearance of cat's eyes or stars in the stone. Aquamarine is hard enough to be scratch-resistant, making it a popular choice for jewelry. Gemstones can be identified by their crystalline structure. The crystal shape of an aquamarine is hexagonal.

Things You'll Need

Jeweler's loupe or gemological microscope
Information on physical properties of aquamarine
Small piece of glass or hardness test kit

Instructions

- 1
  Familiarize yourself with the physical properties of aquamarine gemstones. Refer to print and online resources for photos and descriptions of the characteristics of aquamarine, such as color, hardness, transparency and the crystal shape or internal structure of this mineral.
- 2
  Make sure the gemstone you have is, in fact, an aquamarine by examining its physical properties. Aquamarines are fairly easy to identify, but sometimes the synthetic imitation of spinel (another hard glassy mineral) can be mistaken for aquamarine. The synthetic spinel is colored to a pale blue similar to aquamarine, with the use of cobalt, a metallic element used for coloring substances blue.
- 3
  Examine the color of your gemstone. Aquamarines range from pale blue (almost clear) to a deeper blue or blue-green. Its color is due to trace amounts of iron impurities found within the beryl crystal structure. Aquamarine also displays dichroic qualities, which means it shows more than one color depending on the angle from which it is viewed. Many aquamarines in jewelry stores today exhibit a much deeper blue coloring due to a heating process used by jewelers to eliminate any yellows or greens from the stone. The resulting darker blue stones have become quite popular and cost more than the natural pale blue varieties.
- 4
  Determine the hardness of the gemstone. Aquamarines are hard enough to scratch glass without the stone sustaining any damage. On the Mohs hardness scale for minerals, aquamarine is around 7.5 to 8, with a 1 being talc and a 10 being diamonds, one of the hardest substances on Earth. Perform a test with a hardness kit. For less specific results simply rub the stone across a piece of glass, then check for scratches on the stone and the glass.
- 5
  Identify the internal crystalline structure of the gemstone. Use a gemological microscope or a jeweler's loupe. The crystal shape of an aquamarine is hexagonal and can be seen on the inside of the stone as long, hollow tubes or columns running through the gem.
- 6
  Check with a gemologist or experienced jeweler to confirm any findings you make regarding your gemstone. An expert will have special equipment to perform additional tests on the physical properties of your aquamarine for authentication.

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