QuestionDear Thomas,
I have recently purchased an estate ring with no markings. I was told that it was solid 24K gold and, while I had my doubts, the design was something I had been searching for but could not find for a while. I have since tested it with a tester pen, which came out positive, but that still leaves the possibility that the ring is gold filled. I have also tried the magnet test with similar results. (It is important for me to know, since this is going to be a gift.)
This brings me to the question: Having a bit of a technical background myself, I was wondering how do jewelers tell if a piece is solid gold or gold filled (in a non-destructive manner)? And whether there is something analogous I could try on my own?
Many thanks for your help!
AnswerSam, 24 karat gold is a very rich yellow color and also very soft. You could likely deform the ring by squeezing with you fingers.
Yet, even if not pure gold, the ring very well may be gold and not gold plated or gold filled.
While most testing of this sort is destructive to a point, that "point may be quite small. An easy way is for a jeweler to first do an acid scratch test on an edge of the ring, not on the normally visible surface. If gold plated, when the edge is rubbed against a small slate stone, this will generally cut through the plate. Acid is placed on the rubbing along with a rubbing of a known karat of gold. A comparison is made. If plated, the mark will vanish quickly and a touch of acid to the ring edge where rubbed will generally bubble a bit, something gold does not do. If plated, what have you lost?
If gold filled is suspected as a follow to the above test, the layer is thicker by a large margin than plated but is still relatively thin. A jeweler can take a very tiny round cutting bur and make a slight cut inside the ring. Acid can then be placed on the cut and if a reaction happens the jeweler will be familiar with that and can provide the answer.
If none of this has negative results, a deeper rub may be made and an acid test made on the rubbing to compare for karat. If show to be gold, the edge can easily be buffed back to new like condition.
Ok, as for electronic testers, most of the better ones (also the expensive ones) claim to readily reveal gold plate. Whether or not these will work well with gold filled is an answer I do not have. These tests are certainly completely non destructive. I have a link to a seller of these instruments, a better and recognized brand. I suggest you mail the company as ask if gold filled may be reliably detected. That will give your answer, at least for the various models of their product. Fair enough? (The link is copy/paste)
http://igem-corporation.amazonwebstore.com/TRI-ELECTRONICS-GXL24-ELECTRONIC-GOLD...
Best wishes with hitting it well. We never know at first. : )
God Bless and Peace. Thomas.
