PRECIOUS METALS ACID TESTING
This testing method is what we use ourselves and is not neccessarily correct nor is it the only method of testing with "acid testing solutions". Please do not complain to us if you do not like the results nor if you damage your sample or yourself as we are not liable for damage of any type. Take this advise for what it is worth.
Using Pre-Mixed Acids with a Test Stone
Rub the jewelry on the test stone using 4 firm strokes (two forward and two back) so that a noticeable streak of metal is on the stone. Apply a drop of the pre-mixed acid to the center of the streak. If the metal streak noticeably changes color or disappears, then the metal is less than the karat of the test acid. If the metal streak changes color only slightly, then it has the same karat as the test acid. If the metal streak does not change at all, then it has a higher karat than the test acid. When using a 14K test acid, a 12K gold streak will exhibit a large color change or completely disappear, a 14K gold streak may have a very slight color change, and if the gold is higher than 14K it will not change at all.
Testing Silver
Scratch the article with a file and apply a drop of the pre-mixed acid. If it turns green, it is plated. If a cloudy cream, it is sterling or better. Most Mexican silver generally contains less than 90% fine silver.
Using Pre-Mixed Acids
Find a place on the piece of jewelry where you can file a small groove without ruining the jewelry - the reasoning is to penetrate the thin surface layer of plated metal (if it is plated). Try testing behind a link of a chain if you can. It is fairly common to use karat gold for clasps on chains that are only plated with gold. Apply a drop of pre-mixed test acid in the small groove that you filed. Observe the color change if any and compare same as stone test.
Most jewelry pieces have areas of wear that can be good places to test. Sometimes the wear is enough to remove any plating and testing these areas without filing can confirm that the jewelry is a lower karat than the test acid. If no color change, file a small groove and try again to be sure.
Just for some info
Sterling silver jewelry - .925
Silver gradually softens at room temperature. Other metals are added to form alloys that are less susceptible to scratching and marring with the most common being copper. The result is sterling, which is 92.5 percent silver and 7.5 percent copper (hence the name 925 sterling silver).
417 = 10kt
585 = 14kt
750 = 18kt
Gold filled jewelry - GF
Gold filled is a process of bonding a thin layer of gold to a base metal core, usually brass. Gold filled has an actual layer of gold, giving it more value than plated
