Professional jewelers and jewelry often use gold acid tests to determine gold jewelry’s value. Different acids react differently when dripped on gold. Testing for gold with acid focuses around the fact that gold is a noble metal which is resistant to change by corrosion, oxidation or acid. The acid test for gold is to rub the gold-color item on black stone, which will leave an easily visible mark. The mark is tested by nitric acid, which dissolves the mark of any item that is not gold. If the mark remains, it is tested by applying nitric acid and hydrochloric acid. If the mark is removed, then this test dissolved the gold, proving the item to be genuine gold.
Gold is not a hard metal so there are a number of hardness tests that can be done, although these can result in a partial destruction of the real gold item:.
- A sharp pin should dent a real gold item but will break if the metal is harder than gold.
- The same theory also applies to a bite test, a bite should mark the gold.
- Try scratching glass with the piece of gold. If it scratches the glass, it is definitely not gold, or is mixed with other metals and the purity is very low.
High gold his quality is more yellower. To seek strong ornament and colour desired, pure gold should mixed with other metals. Metals common use for mixture gold ornaments is Copper,Silver, Tin and Nikel. Beside raise different gold strength then metal mixture also to seek colour desired
- Emas Merah – Gold MixWith Copper.
- Emas Kuning – Gold Mix With Silver.
- Emas Putih – Gold Mix With Tin and Nikel.
Genuine gold will not attract a magnet. These precious metals are non-ferrous meaning they are not magnetic. The magnetic test is the most convenient and portable test for genuine gold. If the piece of jewelry is attracted to the magnet, the composition of metals must be a higher percentage of other metals, rather than gold. But having no pull does not
determine it is gold, since it could be made from another non-magnetic material.
Pure gold has a known density, therefore if the volume of the gold object can be calculated. The weight can be extrapolated from the volume and compared to the actual weight of the item. This test was allegedly used by the famous Greek scientist Archimedes. There are many standard Gold Density testing equipment in the market. Measuring instrument in would give gold type in unit Karat.
Sample of Counterfeit Gold