Professional Gemologist Certification Course
Specific Gravity Testing Part 3: Calculating Specific Gravity with an Electronic Scale
Step 1: Equipment and Setup
You’ll need a scale designed for specific gravity measurements, a raised stand, and a hanging basket.
Set the scale on the raised stand, which gives you access to the hanging basket suspended from the underside of the scale. You can then take weight measurements with either the standard balance pan or the suspended basket.
Step 2: Measuring Dry Weight
To calculate an item’s specific gravity, first place it in the balance pan and record its “dry” weight.
For beads or items with difficult to wipe surfaces, it’s important to weigh the item prior to putting it in water.
Step 3. Measuring Weight in Water
Next, place a container of water deep enough to fully immerse the basket beneath the scale. Cold, distilled water with a drop of detergent (dish soap) is ideal. However, depending on how precise you want your results, plain tap water will work fine in most cases.
Tare the balance. (Bring it to zero).
Gently place the item in the submersed basket, ensuring the item is also fully submersed.
Record the weight. Repeat this step at least three times to ensure accurate, consistent…
International Gem Society
When you join the IGS community, you get trusted diamond & gemstone information when you need it.
Get started with the International Gem Society’s free guide to gemstone identification. Join our weekly newsletter & get a free copy of the Gem ID Checklist!