- Shop All
- Mineral ID
- Gem ID
- Specific Gravity
- UV Lamps
- Diamond Testers
- Gold Testers
- Geiger Counters
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! 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 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)|
We developed this particular version of our Universal Specific Gravity Kit primarily for the gem and jewelry trade, and in doing so, we downsized the components to be compatible with virtually any pocket/compact 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.
Parfait. Article conforme, livraison rapide, documentation fournie.
(Perfect. Compliant item, fast delivery, documentation provided.)
Eric Bertrand on Mar 20th 2020
Well packed, items arrived undamaged, easy to setup, which helps in hitting the ground running and collating all the SG data. Albert Tully on Oct 21st 2019
System is perfect for measurements Joan Rosell on Sep 25th 2019
Great product, fits perfectly with my scales. Was very impressed with the fast shipping to Australia. One thing I think would improve would be if it came with a storage bag to protect it when not in use. Highly recommended Mineralab for service. Michelle Honey on Aug 15th 2019
A must-have tool for jewelers! (unless you're a real fan of testing metals with acids.)
Helps distinguish between most common gold, silver, and platinum alloys. No toxic chemicals or scratching needed (as opposed to testing with acids). Cost-efficient (no need to buy expensive Gemoro pens). No more guesswork when a customer asks you to resize a ring they brought from an exotic vacation.
So far, I've tested it with:
- 24k gold (SG around 19)
- 18k yellow gold (SG ~15)
- 14k yellow gold (SG ~13)
Haven't tested white gold yet, but would predict that zinc/nickel alloys would be just a bit lower than yellow gold, and palladium-based alloys just a bit higher/denser.
- sterling silver 925 (SG around 10)
- platinum 950 (SG ~19-20, iridium-based alloys higher ~20-21)
And of course, it helps you determine gemstones, but better use it in conjunction with a spectroscope, filters, and a microscope (or loupe). Tanya on Feb 4th 2019
Exactly what I wanted, well crafted and light so you have more capacity in what you want to identify. Compact size but allows me to ID some of that unknown or mislabeled facet rough. Thomas Reeves on Apr 16th 2018
Very very happy! 180€ in France 96 with you shippemend included. Very good material! jeremy guelle on Feb 7th 2018
This item is exactly what I wanted. I have a small desk space and I needed an accurate SG kit to fit the space. It was easy to set and has proved to be reliable and accurate Unknown on Jul 21st 2017