Specific Gravity or Relative Density is the ratio between the weight of the stone in air and the weight of an equal volume in water. The two commonly used ways to determine the specific gravity of a gem or mineral is by using heavy liquids or hydrostatic weighing.  Gravity is a measurement of the relative density. Relative density is a comparative scale.  Using heavy liquids to measure specific gravity, a gem will either sink, float, or rise to the surface depending on its specific gravity in relation to the liquid. The Specific Gravity measurement helps identify an unknown gem, mineral, or other material.  The specific gravity is calculated by the hydrostatic balance using Archimedes Principle.

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