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18k yellow gold pieces getting brownish stains


#1

A pair or earrings, after being worn a few days, showed very dark
brownish stains. I’ve tested again, and it is 18k, according to the
touchstone test. Please, help me to understand why it happened. Could
it be due to some undesirable impurity in the alloy components? I
bought the metal from my usual dealer. He states that the alloy was
made using copper from electric cable wire and 999 silver. I’ve been
making jewelry for about ten years, and so far, never seen anything
similar. Thank you. Regina


#2

Regina,

could it be the body chemistry of the one wearing the earrings? Rose
Alene McArthur

@O_B_McArthurs


#3

Dear Regina;

I have seen cases where karat gold turn brown reacting to chlorine.
If your customer is cleaning them by soaking in bleach, this could be
the problem, or they could be spending a lot of time in the swimming
pool. I would expect 18K to be less likely to react this way, but
I’m sure others will have further suggestions.

David L. Huffman


#4

We have found over the years that some batches of metal will show
some color change. I have always believed it to be part of the
reaction of the particular batch of metal used to the acids in the
wearers skin—at that time. I have a band I have been making for a
long time that I wore a version of. Over the period of about 6 months
it developed a highly unusual bronzy-brown antique type feeling. I
sold the ring off my hand to a customer, only it needed to be sized
for her. When we heated it to size it, of course, the color change
disappeared. Unfortunately, I then had to spend considerable time
consoling the customer, as that was one of the elements of the ring
that she liked the best! I haven’t had any other rings I wear do the
same thing, however I have had customers who bring in pieces that
have definitely changed color with wear. We have also found some
variation in color from similar manufacturers depending on the
particular batch of metal used.

Daniel R. Spirer, GG
Spirer Somes Jewelers
1794 Massachusetts Ave.
Cambridge, MA 02140
@spirersomes
http://www.spirersomes.com


#5

Daniel;

I have found that it seams that each gold foundry will have their own
’pet’ percentage of alloy mix—yet equal the proper standard karat .
Which can react differently to individual body chemistry…Also you
must expect to allow for different commercial solder qualities.
Next: Note; A lot of bronze artists use --'pregnant camel urine
to create --‘that’ patina we all come to love…


#6

To all for what it’s worth,

Having been in this business for twenty plus years, I have heard a
multitude of scientific “reasons” that cause gold smudge. My wife
recently heard, on the radio, a discussion by an “expert” that stated,
after much study, it to be caused by a iron deficicency in the person
wearing the item, developing an “ionic” reaction to the alloys in the
metal. This supposedly explains why you can wear a piece for years
without incident, then suddenly develope the problem. A day or two
later, you may be able to wear the same piece without problem if your
body regulates itself with the iron-rich foods which it will crave.
Longer term problems can be corrected with iron supplements.

I have absolutely no other as to the credibility of the
speaker in this case, however maybe other more learned members of this
forum could shed some light
on the subject. JMF


#7

A definite possibilty. Sweat is a great corrosive (oxidizing) agent
due to its salt content. There are a lot of articles on sweat induced
oxidation/corrosion of metals in early 60s’ British Corrosion Journal
and Materials performance. Kayce

Kayce Chidambaram Ph.D.
Principal R&D Chemical Engineer
The Bell Group
7500 Bluewater Road NW
Albuquerque NM 87121-1962
Tel: (505) 839-3523
Fax: (505) 839-3525