How To Modify A Powder Scale for Specific Gravity Testing


Powder scales are commonly used to measure precise amounts of gunpowder when handloading firearm ammunition. These scales are very accurate and easy to use for measuring small objects, perfect qualities if you’re also working with gemstones. Gemologists can modify a powder scale for specific gravity testing, an important method for identifying gems. This article will take you through the modification and testing process step by step.

How To Use A Powder Scale

You can find both electronic and beam-type powder scales for sale. The beam-type RCBS Model 505, available through Amazon, is highly recommended and inexpensive. (We’ll use the beam-type scale as our example). Powder scales uses “grains” as a unit of measure. One carat equals 0.324 grains.

As with any beam scale, you must zero a powder scale before weighing anything on the pan. Adjust the tenth, one, and ten-grain weights on the beam until the marker opposite the pan sits at zero before every measurement.

Specific gravity or density in gemology is the ratio of the weight of a gemstone to the weight of an equal volume of water. To determine the specific gravity of a gemstone requires two measurements: the weight of a gemstone in …

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