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An Electronic Scale can be used to measure the specific gravity of gemstones. As with most hydrostatic devices, you simply weigh the stone "in air" and then weigh it in water. A typical scale intended for such purpose has a "weigh below" hook on the underside of the scale from which to suspend a "gem holder" in a container of water. While this works for a weighing of the stone in water, it is an awkward operation - the scale must be elevated on a stack of books or the like, and the user must work in a confined space underneath it.
Mineralab has, instead, developed a very user-friendly "above the scale" underwater weighing process, along with a Universal Specific Gravity Kit (see photo above). Just weigh the stone "in air" on the integrated weighing platform of the scale, then without changing any setup, weigh the stone in water by placing it in the underwater weighing pan of the gem holder suspended above the platform. Then plug those two values into the Specific Gravity equation to obtain the specific gravity of your stone. It's that easy and it takes only a few seconds!
The photo above shows the components of our Universal Specific Gravity Kit, and how it is utilized with an Electronic Scale. A beaker of water sits within a spill-resistant support independent of the scale itself, while a lightweight gem holder rests on the scale's weighing platform, with the weighing pan suspended underwater. The components of our Specific Gravity Kit include the following:
|Lightweight Gem Holder Support and Underwater Weighing Pan|
|Independent, Spill-Resistant, Adjustable Beaker Support|
|Beaker for filling with water - 50ml capacity, with approximately a 1.6" inside diameter.|
|Aluminum Test Weight whose SG = 2.70|
|Stainless Steel Tweezers|
|Complete instructions (although this method is very simple)|
|Table of 100 common gems sorted by specific gravity, with 6 other properties, including refractive index. (Or purchase our Mineral Search software and let your computer do the work of searching a gemstone database by specific gravity and other properties)|
This version of our Universal Specific Gravity Kit can be used with virtually any pocket Carat scale, provided that:
For those who need accurate specific gravity measurements on small, lightweight gemstones, these further criteria are necessary:
This item typically ships within 1 business day.