Testing gold is absolutely necessary when selling your golden jewels or buying such from an unaccredited source. Although most gold products have carat stamps, sometimes old unstamped jewels appear on the market. The stamps can also be forged and placed on fake jewels or ones that are excessively dirty and questionable.
When the jewel is unmarked or you have doubts concerning the authenticity of the stamp, the easiest way to test the gold content in it is with the so-called acid test. It is among the most popular methods of testing because it does not harm the golden ornament and it has no effect on the carat or weight of it and thus reducing its price.
The technique of testing gold with acid can be easily mastered. All you will need is a rubbing stone, an acid kit, and a few stamped and approved golden jewels. The stone is usually small, around 4-5 cm in diameter. It can be in the shape of a rectangular plate, an oval, round or an irregular shape. Its shape has no effect on its properties and does not influence its work. The more important and essential part of the gold testing kit is the acids. In the kit, there are usually several acids for testing 10, 14, 18, and 22-carat gold.
The testing of each golden jewel begins with observation under a magnifying glass. Look carefully for any marks that can give you a starting point for the carat testing. If you find a mark for 14-carat gold (the stamp should read 585), start the procedure with the corresponding acid for 14-carat gold. If there is no mark or stamp to direct you, start with the acid for the lowest carat – usually 10.
- Take the gold and rub it on the stone until it leaves a golden trace. Although this does not harm the jewel, it is still preferable to do it on the backside of it. Do not rub too vigorously or too hard.
- Drip a drop of acid over the golden trace. The acids are typically sold in dropper bottles, but if yours are not, then use a pipette, different for each acid. If the trace disappears immediately, this means that the carat of the jewel is lower than the carat of the acid. Wipe the stone with a paper towel to make sure it is completely clean.
- If, after testing with 10-carat acid, the trace still remains, this means that the jewel is with a carat equal to that of the acid and possibly higher.
- Continue testing it with the 14-carat acid. If it is able to dissolve the golden trace, that means that the jewel is with a carat higher than 10, but lower than 14. This is quite possible. It is a rarely known fact that the carat of Russian gold jewelry is lower than 14 and is usually around 13.
- If the golden trace remains after the 14-carat acid test, continue testing with the 18- and 22-carat ones until you are able to determine the proper carat of the jewel.
There are also acids for testing 9- or 24-carat gold but are rarely found on the market, because it is unlikely that you will ever come across a jewel with 999.9 purity of gold.
When the carat is determined, the jewel is weighed and the customer receives an estimation of its value. This procedure is usually performed by professionals. For customers, the satisfaction of knowing that their gold is not damaged or devalued is enough.