Specific Gravity Test For Gold And Quartz Specimens:
Figure out how much gold is in a quartz gold specimen. The simplest way to test specific gravity is weigh the quartz gold specimen in “air” and multiply the weight by 1.9. Then weigh the quartz gold specimen fully submerged in “distilled water” and multiply that weight by 3.1. Minus the wet figure from the dry figure and you will get a fairly accurate specific gravity for that specimen!! You can then approximate how much pure gold is in the piece by using the numbers above. (this formula assumes relatively pure quartz with no pyrites or other country rock attached and 85% pure gold in the specimen)
The way I do the test is to place my regular old digital scale on the backs of 2 chairs so that I can put a piece of coat hanger across the weighing platten and hanging a string down from each end like a swing.
Attach a rubber band to the 2 strings so that it will “hold” the specimen.
Tare out the scale to 0.00
Attach the quartz gold specimen to the string to weigh it first just hanging “dry”
Now bring a container of water up under the specimen and make sure the specimen doesn’t touch the sides or bottom of the container, you may have to place the container on some books, or bricks etc so that the water doesn’t slosh around and give false readings
These following numbers are specific gravity of certain materials:
Sterling Silver 10.36
Coin Silver 10.31
10k yellow 11.60
10k white 11.60
14k yellow 13.40
14k white 13.40
18k yellow 15.50