Electronic Scale

An Electronic Scale can be used to measure the specific gravity of gemstones and minerals. 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 - 50 to 100ml capacity

Aluminum Test Weight whose SG = 2.70

Stainless Steel Tweezers

Complete instructions (although this method is very simple)

Table of 300 common minerals/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 gem and mineral database by specific gravity and other properties)

Our Universal Specific Gravity Kit can be used with virtually any electronic scale, including both Bench Scale models (above) and Carat Scale models (right), provided they have a tare (re-zeroing) function.

Additionally, for the Bench Scale version, your scale must have a minimum capacity of 50 grams, while its weighing platform must accommodate the 3.25" diameter base of the kit's Gem Holder Support. The "tared weight" of that portion of the kit that sits on the weighing platform is about 26 grams, so this must be subtracted from your scale's listed capacity to derive available capacity for specific gravity measurements.

For the Carat Scale version, your scale must have a minimum capacity of 50 carats, while its weighing platform must accommodate the 1.75" diameter base of the kit's Gem Holder Support. The "tared weight" of that portion of the kit that sits on the weighing platform is about 40 carats, so this must be subtracted from your scale's listed capacity to derive available capacity for specific gravity measurements.

For those who need accurate specific gravity measurements on small, lightweight gemstones, these further criteria are necessary:

The weight range of the scale should accommodate specimens as light as possible, say with a Readability down to .001 to .002 grams (.005 to .01 carats) If money is no object, the scale should read down to .0001 grams. Refer to this Table for details on how accurate and sensitive a particular scale will be for specific gravity measurements.

The scale should provide for calibration, either internally or through the use of calibration masses.

The scale should offer readout in carats, in addition to grams.

Make your selection below to order our Universal Specific Gravity Kit, choosing between the Bench Scale version, or the Carat Scale version. This product typically ships within 24 hours.

Beyond our Universal Specific Gravity Kit, if you also need an Electronic Scale itself for specific gravity measurements of gems or minerals, click on this link or the navigation button above for our recommended selection of Models of Electronic Scales.

Discounts: This product is available to Dealers for resale purposes at wholesale prices, and to Schools, etc. when purchased in quantity. Please contact us for further information.

Back to overview of Specific Gravity devices

Qty: SKU: SGK Price: $79