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Specific Gravity Kit for your Bench Scale

2.00 LBS
  • Product Description

    An Electronic Scale can be used to measure the specific gravity of gemstones and minerals, or any solid for that matter, including industrial materials.  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 suspended above the platform.  Then plug those two values into the Specific Gravity equation to obtain the specific gravity of your material.  It's that easy and it takes only a few seconds!  See our YouTube video below:

    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 Underwater Weighing Pan assembly rests on the scale's weighing platform, with the weighing pan suspended underwater.  The components of our Specific Gravity Kit include the following:

    • Lightweight Underwater Weighing Support and Pan
    • Independent, Spill-Resistant, Adjustable Beaker Support
    • Beaker for filling with water - 100ml capacity, with approximately a 2.2" inside diameter.
    • Aluminum Test Weight whose SG = 2.70
    • Stainless Steel Tweezers
    • Complete instructions (although this method is very simple)
    • Table of 300 common minerals 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)

    This version of our Universal Specific Gravity Kit can be used with virtually any Bench or Lab size Electronic scale, provided that:

    • The scale has a minimum capacity of 50 grams.
    • FYI, 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.
    • The scale has a tare (re-zeroing) function.
    • The scale's weighing platform is large enough to accommodate the 3.25" diameter base of the kit's Underwater Weighing Pan Assembly.
    • If the scale has a draft shield or lid, it must be either removable, hinge back away from the scale, or designed such that the front and 1 side door can be opened.
    • If your scale has a draft shield that remains in place, its inner dimensions must be large enough to fit our Tri-Wire Weighing Pan Assembly which is 7" high and 4.5" across.


    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 Sensitivity 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 ideally offer readout in carats, in addition to grams.

    This item typically ships within 1 business day.

  • Product Reviews


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    1. Easy and accurate

      I purchased this kit for the large scale in order to help identify several rocks minerals in my shop that I’m not really sure what they are! I purchased the larger size version planning on purchasing a larger scale currently I’m using this large version with my portable scale and it works just fine! I’ve already used several times and has worked great! on Jun 10th 2022

    2. SG KIt

      The kit is well made and a good simple device for quickly identifying gems/minerals etc. Delivery was very quick, would recommend. on Aug 6th 2019

    3. Specific Gravity Bench Scale

      Well done. well made. I have the Hanneman Balance also, the 2 together make my identification of gems & preciuous metals easy. Thanks Patrick on Dec 10th 2016

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