SG in gold stands for Specific Gravity.
Understanding Specific Gravity in Gold
Specific gravity is a measure of the density of a substance compared to the density of water at a specific temperature (usually 4°C). Essentially, it tells you how much heavier or lighter a material is than an equal volume of water. A higher specific gravity means the material is denser.
As stated in the reference, pure gold has a specific gravity of 19.3. This is a very high value compared to most other metals, which is why gold feels significantly heavier than many common materials. For example, the reference highlights that pure silver has a specific gravity of 10.5, making gold feel almost twice as heavy for the same volume.
Here's a quick comparison based on the reference:
| Metal | Specific Gravity |
|---|---|
| Pure Gold | 19.3 |
| Pure Silver | 10.5 |
This significant difference in specific gravity is a key characteristic that helps distinguish gold from other metals.
Practical Applications: Testing Gold
The unique specific gravity of gold is not just an interesting property; it has practical uses, particularly in testing the authenticity and purity of gold.
- Density Comparison: Because pure gold is so dense (SG 19.3), anything that is not pure gold or is a less dense metal mixed with gold will have a lower overall specific gravity than 19.3.
- The Archimedes Water Test: As mentioned in the reference, the specific gravity can be used to test whether something is silver or gold, or to assess the purity of gold. The famous Archimedes water test is a method based on specific gravity. By weighing an object in air and then weighing it submerged in water, one can calculate its volume and thus its specific gravity. Comparing this calculated value to the known specific gravity of pure gold (19.3) helps determine if the object is genuine pure gold or an alloy/imitation.
In summary, SG is Specific Gravity, a crucial physical property of gold (19.3 for pure gold) that explains its characteristic weight and is used as a fundamental method for testing its authenticity and purity.
