using heavy liquids for SG testing - bromoform
using heavy liquids for SG testing - bromoform

Specific Gravity Testing Part 5: Using Heavy Liquids


Using heavy liquids to measure a gemstone's specific gravity poses some health hazards. Learn the techniques and precautions that gemologists take.

2 Minute Read

The Gemological Institute of America (GIA) offers a set with densities of 2.57, 2.62, 2.67, 3.05, and 3.32. Other manufacturers offer sets with different ranges.

Before Using Heavy Liquids, Know the Risks

Most heavy liquids are solvents, in the same family as thinners, and toxic. Don't inhale their vapors or get any on your skin or clothing. Heavy liquids are also flammable, so keep them away from heat sources at all times. Follow all the manufacturer's safety instructions for whatever set you choose.

You can learn more about gemology and lapidary safety here.

Why Use Heavy Liquids?

The theory behind using heavy liquids is simple. If you put a gem in a liquid with the same density, it'll stay in place. Should the gem have a greater density, it'll sink. So it follows that the gem will float if it has a lower density.

How fast the gem sinks or floats will give you some indication of how much its specific gravity varies from the liquid's. If the difference is just a couple hundredths of a point, it will drift slowly up or down. A difference of a...


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