How to Identify Types of Gemstones

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Gemstones are beautiful and may be valuable or even rare. A professional gemologist can identify the gemstone definitively. However, before going that route, it may be possible to make an educated guess about what type of gemstone you have with the use of some tools appropriate for the task.

Examine the color of the gemstone to discover clues to its identity. A blue gemstone may be a sapphire, aquamarine or turquoise, but it probably is not a garnet or an emerald, which are red and green, respectively. The color in gemstones is usually the result of a small amount of metal ions in the stone. Diamonds are commonly thought to be colorless, but nitrogen atoms can cause blue and yellow coloration.

Use a jeweler’s loop with 10-power magnification to determine the transparency of the gemstone. Some gemstones are transparent, like diamonds, and some are opaque, like opals.

Look for distinctive phenomena because of the way the gemstone interacts with light like asterism, which is demonstrated in a star sapphire. Other optical effects displayed by gemstones are shimmering, glowing and flashing. Knowing about phenomena and the gemstones they are identified with can help to narrow down your choices when you identify your gemstone.

Judge the luster of the stone as light is reflected from it. A gemstone may have a metallic luster or appear dull or waxy. Look at the dispersion of white light into spectral colors, often referred to as “fire.” Some gemstones, like diamonds, are known for their fire.

Examine the cut of the stone, which can provide clues to its identity. Some cuts like oval, emerald cut and baguette are associated with particular stones.

Look for tell-tale signs that the stone is synthetic and not a natural gemstone. A curved growth pattern and inclusions like gas bubbles and “platelets,” remnants of the container used to create the synthetic, can indicate that the stone is not real. Color, fluorescence and fire are some of the most important indications for identifying a genuine diamond.