Every metal has a specific density that can be calculated when submerged in water. This is a great tool to double check the gold and silver you are buying if they are the real deal.
Unfortunately, counterfeits are on the rise, and they are made exceptionally well. Specific gravity is one way to verify that you aren’t purchasing a counterfeit.
In this post, we are going to go over how to do a basic calculation for specific gravity of any metal. It is an inexpensive and non invasive way to test your gold or silver without damaging the items.
The actual professional testers can cost thousands of dollars, and the truth is, all they really do different than setting up your own, is they do the calculation for you. You can learn how to build your own specific gravity tester for a fraction of the cost here:
The Method
To measure the gold purity using this method, we are going to use a calculation of our gold item submerged in water.
Here’s what you will need.
Glass or plastic see through container that is big enough to fully submerge your item in water without touching any of the sides or bottom.
Pure filtered water – enough to fill your container to fully submerge your item.
Jewelry scale
Stand or mini tripod – if you don’t have you can use a small piece of wood and a stack of books
Dental floss or thin string
Step 1. Weigh your item on the scale.
Step 2. Put cup of water on the scale and zero the scale
Step 3. Tie your string around your item
Step 4. Set your tripod or wood block over the cup and submerse the item in water without touching the sides or bottom.
Step 5. Get weight of the item on scale.
Step 6. Divide the original weight of your item by the weight of your item submerged in water.
Step 7. Match your calculation with the specific gravity to find out the metal purity in the chart below.
Once you determine the specific gravity, it is important to note that tungsten gold bars are almost the same specific gravity as 24k gold bars. Tungsten’s specific gravity is 19.25 and 24k gold is 19.32. Given these two are so close together, if you are still second guessing and are buying large quantities of gold, you may want to consider the sigma metalytics precious metals tester which penetrates the item above the surface and tests the resistance of the metal.
Troubleshooting Specific Gravity Calculation
General Information
When doing the calculations, all items are going to be different when handling the calculation. The more solid the item, the easier it is. This method works extremely well with solid gold and silver coins, bars, rings, necklaces, etc. It becomes more challenging when you have light weight items that have small gaps. This is the case even with specific gravity testers that cost thousands of dollars.
Solid items are much easier to calculate than items that have spaces in between. For example, a heavy necklace will likely result in less air bubbles versus a light weight chain with skinny links. The reason is because air bubbles can get trapped in the water and affect the calculation.
That is not to say you cannot get a solid calculation, but it can be a challenge. Sometimes spraying rubbing alcohol on the item before you submerge it can lesson the chance of air bubbles sticking to the item.
Getting different results with the same item
It is most common to get different results from the smaller items. This is mostly because of air bubbles getting trapped in the water. If you are getting a handful of readings, it is best to redo your test until you get a repeat of the same results (or close to) at least a handful of times.
Testing with diamonds, and other gems
You cannot perform this test when there are stones, diamonds, gems, etc because it will throw off the sg reading. The only way you can perform this test is if you remove the diamonds.
Scale is not zero
Tare your scale and it should then read zero. Turn it off and wait a few seconds to turn back on, and should read zero.
