Frequently Asked Questions
Gold and tungsten have nearly the same densities. Gold is 19.3 grams/cc and tungsten is 19.25 grams/cc. Counterfeiters exploit tungsten’s high density to mimic gold and fool unsuspecting investors. Gold coins are being manufactured in China and can be purchased on the internet for less than $300. Spot price for an ounce of gold (Oct 2015) is about $1,200. Unscrupulous gold sellers could quadruple their investment.
#1 – Research specification of the test coins you’d like to validate (i.e. weight, diameter and thickness).
#2 – Weigh the test coin. Use a quality scale and verify its accuracy by weighing a known authentic coin. The weight of the test coin should be within plus or minus 0.1 grams. Too light indicates that the coin metal’s density is too low such as silver or copper in gold coins or non-magnetic stainless steel in silver coins. Too heavy indicates that too much tungsten was used to make the fake coin.
#3 – Check the diameter and thickness of the test coin with a set of calipers. These measurements must match exactly. Any deviation should be considered a fraud.
#4 – Perform a ring test on silver coins. Drop the silver test coin on a hard surface such as a table. A silver coin possesses a clear distinctive enduring ring. A fake silver coin will give a dull thud instead of a resonating ring. Drop a real silver coin and listen to the ring.
#5 – Check silver coins with a neodymium rare earth magnetic slide. Silver is diamagnetic and repulses the magnetic field. A silver coin will slide very slowly but a stainless steel fake will slide fast. This product will be offered for sale to the public in the future.
#6 – If the composition of the test coin is still in question then an Archimedes’ density test should be performed. Density is measured in grams (g) per cubic centimeter (cc). First step is to weigh the target coin. Second is to place a container of water on the scale and zero/tare the scale. Third is to tape a thread onto the coin and submerge. It is important not to let the coin touch the walls or bottom of the water filled container. Record the weight while the coin is suspended in the water; this weight is the amount of water displaced. Water’s density is 1.0 g/cc. To determine the density of the test coin; divide the weight of the coin by the weight of the displaced water.
Densities of some precious metals and common metals used for counterfeits:
Water (H2O) – 1.0 g/cc
Stainless Steel – approximately 7.84 g/cc
Copper (Cu) – 8.96 g/cc
Silver (Au) – 10.49 g/cc
Lead (Pb) – 11.34 g/cc
Tungsten (W) – 19.25 g/cc
Gold (Au) – 19.3 g/cc
Platinum (Pt) – 21.45 g/cc
Densities of common precious metal coins:
Platinum Maple Leaf: 100% platinum – 21.45 g/cc
Gold American Eagle: 91.67% gold, 3.00% silver, 5.33% copper – 18.48 g/cc
Gold Vienna Philharmonic: 100% gold – 19.3 g/cc
U.S. Double Eagle: 90% gold, 10% copper – 18.27 g/cc
U.S. St. Gaudens: 90% gold, 10% copper – 18.27 g/cc
Gold Buffalo: 100% gold – 19.3 g/cc
Gold British Sovereign: 91.67% gold, 8.33% copper – 18.44 g/cc
Gold Canadian Maple Leaf: 100% gold – 19.3 g/cc
South African Krugerrand: 91.67% gold, 8.33% copper – 18.44 g/cc
Silver Canadian Maple Leaf: 100% silver – 10.49 g/cc
U.S. Silver Dollar: 90% silver, 10% copper – 10.34 g/cc
Calculated densities from the test results should be close (+ or – 5%. If they are not close then the test coin is a counterfeit.