Recognize the real and the fake : methods
Gold is a highly dense metal, giving it the distinction of having a weight / high volume. To simplify, if filled récipientd’une a capacity of one liter with pure gold 99.9%, we get a weight of 19.3 kg.
The unmelted native gold (from artisanal gold mining) that we put in a beer glass 25 cl weigh between 3.5 and 4.5 kg, depending on the shape of flakes and nuggets. The density of weighing is also often used to buy this type of gold.
Plated jewelry always gives an impression of lightness compared to its volume. More titration of gold jewelry is, the more it is proportionately heavy. For example, the density of 18 karat gold is 15.5-16 g / cm3.
Finishing touch and manufacturing style of jewelry
A gold jewelry is mostly metal end time because gold is expensive and is often sought to maximize their weight-volume. Too thick in the style of making jewelry should make you cautious and wary.
The chains or bracelets terminating flat rings can be an indication plated jewelry as the presence of small triangular plates before endings. We can also say that a plated jewelry is made of coarser or industrially.
Few chemical solutions are capable of dissolving gold. Unless of course one : aqua regia. However, aqua regia is an unstable solution can not be stored in liquid form for very long.
Therefore, it was designed to “aqua regia softened,” specifically used acids to test the gold and thus know the carat jewelry. This type of test is commonly called gold to test the touchstone.
The acid solution is composed of the following mixture :
- Nitric acid, also called azotic acid whose chemical formula is HNO3
- Chlorydric acid whose chemical formula is Acide chlorhydrique, de formule chimique H3O+ Cl–.
We use in large quantities using nitric acid in the mixture due to its oxidising properties. Metals such as nickel, cobalt, copper, mercury, silver, lead, selenium, bismuth, zinc and cadmium dissolve in nitric acid.
The test touchstone among the oldest method of analysis of precious metal alloys. The black jasper is the stone must be of good quality in order to have the assurance of a reliable test. So beware stones synthetic key, whose quality is lower does not guarantee a good result!
The test is performed as follows.
1. Please have a touchstone of 18K acid and gem testing.
2. Rub your jewelry on the stone in order to leave a significant trace.
3. Spend your 18K acid on the track and watch the reaction.
- If the trace remains intact, the jewel is therefore 18K gold.
- If the mark turns red, the jewel is one carat less than the acid.
- If the trace disappears, the jewelry is gold plated.
In case 2, we deduce that the jewelry is in 14 carat because the track became red in the passage of the acid 18k. If we would have passed the acid 14k and we have observed the same reaction, we would have deducted while the jewelry would be 9 carats.
The reaction of the case 3 is explained by the fact that nitric acid dissolves completely copper, present in very large quantities in the alloy of gold-plated jewelry.