How Do You Identify Rough Gemstones?

Identifying rough gemstones is a multi-step process that involves testing the hardness, streak, the shape of the stone, also known as crystal morphology, and the cleavage. Chemical testing may also be necessary.

The first step when identifying a rough gemstone is to determine if it is truly a gemstone. Rough or sandy stones are not gemstones, despite how lovely they may be. If the stone is easily shaped by hammering or bending it, the stone is more likely a bit of metallic ore. Gemstones are crystalline in structure and do not bend or shape from these methods.

To help put the gemstone into the right category, test the hardness using a Mohs scale. This scale tests from 1 to10, with 1 being talc and 10 being diamond. Testing hardness requires a hardness kit. Cleavage should not be tested if the gemstone is suspected of being an valuable stone, such as a diamond, as the testing requires striking the stone to view fracture lines to identify the stone. Instead, take the gemstone to a professional to have it identified.

Many gemstones also leave a streak of color on a ceramic plate and this color can be compared to a streak chart to help in identification. Not all gemstones leave a streak. Examining the crystalline structure of the stone also narrows down the type of gem. Color identification should be left until last as many gems come in a variety of colors.