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Black gold


#1

Greetings all, while browsing through some shops the other day,
I came across an 18K gold band, nothing exciting except that it
was black. It already appeared to have some signs of wear, with
a yellow colour showing through in one area, so I assume that it
is not very durable. I was wondering how this colour is
produced, any ideas?

thanks,
murky


#2

Here’s my guess: it had to be copper plated and then the copper
changed to black copper sulphide in a sulphide bath - and like
you said, it wouldn’t be very durable. But why the hell would
anyone want to hide the beauty of 18 ct gold? Yuck!! And
Cheers,

       / \
     /  /
   /  /                                
 /  /__| \      @John_Burgess2
(______)       

At sunny Nelson NZ


#3

Doesn’t Have to be copper plated… Just anneal a piece of 18K
in an oxidizing flame, no boric acid coat. Nice low red heat.
Let cool gently. Viola. Black gold… So, perhaps the band
you saw was someones, and they left it on the stove or
something… (grin)

Peter


#4

Hi murky In answer to your question, it is possibly Rhodium
Plated with a Black rhodium Solution. (Same as normal Rhodium
Soln only black)

Lawrence


#5

I’ve been hearing of black gold. Is it an alloy? If so, I’d love to
know how to make it, for 18 karat. Or is it just a matter of rhodium
plating on white or yellow? Thanks,

Regina


#6

Hi All, I’m on vacation on St. Maarten and couldn’t resist drifting
thru the jewelry shops near where the cruise ships come in. I saw
something new this morning. Black gold. It was a line of very fine
wire wrapped work, done in a very black gold which they assured me
would not wear off. I’m counting on someone to tell me what it is.
The shop owner said it was done with oxidation. I am very curious
indeed.

Thanks, Betty


#7

I too want to know how it is done. I saw on one of the home
shopping, a black pearl ring , but the pearl was really gold. They
exlained that it was not a patina, but black through and through.
They even went so far as to cut it open and show it was. It was
gourgeous. I haven’t been able to find anyone who knows.


#8

Betty’ Try contact Argen corp. www. argenjewelry.com Their salesmen
offered me black castable gold in 14 and 18K .believe they are in San
Diego CA.

usual disclaimer.

Rafal


#9

A timely advertisement: Argen has an ad on page 69 of the new
Metalsmith magazine (Spring 2003), offering black, purple AND other
colors of gold! www.argen.com 858-455-7900 Linda


#10
    A timely advertisement: Argen has an ad on page 69 of the new
Metalsmith magazine (Spring 2003), offering black, purple AND
other colors of gold!  

I contacted Argen, The black gold is an oxidation layer over a
special alloy that can only be cast using inert gas shielding of the
melt and casting process and is brittle just like purple gold. It is
not a bulk metal color. There is no bulk metal coloring of gold that
yields black all of the processes are surface coloration either
patinas, oxidation or an actual coating applied by electroplating or
plasma vapor deposition. So they are basically laboratory
curiosities but not really a useable product as the coatings all
scratch off after time(the Plasma Vapor Deposition is a very durable
coating but it is still a coating and will wear through).

Jim


#11

Hello, my name is Chad Rutledge and I am a beginning jeweler. I have
been soaking up as much as possible for the past two years. Recently
I noticed some hip hop artist wearing blackish looking chains and
charms. Which caused me to start researching the possible materials.
I have seen a few (and I literaly mean A FEW) places that advertise
BLACK GOLD! So, I started looking up Black Gold, and it seems like
the on the material is just as scarse as the material
itself. My hopes are that someone on here may know either, where to
find out more about black gold, where to buy black gold stock to work
with, or basically anything to do with black gold that will help me
in my journey to discover everything there is to know about the
material!!! Any help would be highly appreciated.

Thank you in advance
Chad Rutledge


#12
Recently I noticed some hip hop artist wearing blackish looking
chains and charms 

Neither gold, nor any of it’s alloys, is black in color. That
includes those chains and items you saw.

Black colored metal, with gold or something else, is generally a
surface patina or a coating. with silver, it’s easy and common to
blacken the surfaces with liver of sulphur or another oxidizing
solution. With low karat golds, you can do similar things with
commercially available gold/silver oxidizers, which are a bit more
than just liver of sulphur.

You can also use electroplated coatings, such as black rhodium,
black nickle, or similar electroplated coatings. Some of these are
better than others in terms of durability, but it’s an issue with
most of them.

In recent years, we’ve seen high tech coatings used to get various
colors, black, brown, purple, red, and others, on any number of
jewelry metals. Some of these are vapor deposition coatings, but the
majority of those chains that I’ve seen, seem to be a sort of ceramic
coating. Not sure exactly what. But this isn’t simply a “studio
goldsmith” sort or technology, and it’s not dependent on the alloy
used.

Peter Rowe


#13

Hello Chad,

Gold is deep yellow and in matter of fact, it is of the same "family"
as copper which is the next metal with a specific color other then
gray or white… In use with alloymetals (precious or not) you can
create different goldcolors like pale yellow, red, pink, bleu, green,
purplisch etc. However black gold is not one of them. The way of
making it black is by the use of chemicals (patina’s) or by other
means like using zirconium in a complicated process PVD (physical
vapor deposition) Black hills gold however exists but has nothing to
do with black gold

With all respect and by all means, It whould be preferable and
advicable when you learn the basics first as a beginning jeweler
before one jumps into a black area but this is up to the person
himself.

I’ve learned it the hard way, payed for my mistakes and believe me I
still don’t know everything but you learn as you go allong.

Enjoy and have fun
Pedro


#14

Chad, what you want is here. It took three seconds to search it out.

Bill, Deborah, Michele & Sharon
Reactive Metals Studio, Inc


#15

From:
http://www.newsletter.kaijewels.com/gold-colors.htm

Black Gold is today possible using quite a few techniques.
Electrodeposition using black rhodium or ruthenium is one method.
Amorphouse carbon is also used at times, with the Plasma Assisted
Chemical Vapour Deposition process. Controlled oxidation of carat
gold containing chromium or cobalt can also be made to yield
black gold. Ruthenium containing, electroplating solutions give a
slightly harder black coating as compared to electroplating
solutions that contain rhodium.

#16

See “Colored Golds” by Cristian Cretu and Elma van der Lingen, Gold
Bulletin, 1999, Vol.4 for detailed technical explanation Re: how
color appears in gold alloys. The section on black gold does refer to
surface oxides, but these can be produced by including certain metals
in the alloy when alloying rather than adding a layer by various
means afterwards. This could be considered as “alloying black
gold”…

From the article (please note that subscripts are not printable here,
so the necessary changes need to be made when reading…):

"Black gold generally contains cobalt, which forms a black cobalt
oxide layer on the surface with heat treatment between 700 and
950A1C (50, 51) (Figure 22). Other alloying elements also known to
give a blackish layer on oxidation are copper, iron and titanium.
Black gold alloys also contain at least one of the platinum-group
metals, silver, or nickel. Van Graan and Van der Lingen (52) improved
the wear resistance of 18 carat cobalt-containing gold through
chromium additions. An electrolytic hardening cycle such as that used
after the colouring of stainless steel was incorporated (53). The
addition of chromium results in a thinner oxide layer which consists
mainly of Cr2O3 and has an olive-green hue. The wear resistance of an
Au15wt%Co10wt%Cr was significantly better than that of a binary
Au25wt%Co alloy, although the oxide layer was approximately five
times thinner (Figure 23). The microstructure of the alloy in Figure
23 is composed of a gold-rich phase containing ca94wt%Au and a
cobalt-rich phase containing ca90wt%Co. Between the CoO layer and the
matrix, is a cobalt-depleted zone containing only ca2.4wt%Co,
resulting from cobalt segregation to the surface during oxidation.

Janet in Jerusalem


#17

argenjewelry.com sells an 18 Kt Black casting alloy. The table says
it contains Au, Co, Ir.

Janet in Jerusalem


#18
argenjewelry.com sells an 18 Kt Black casting alloy. The table
says it contains Au, Co, Ir 

We tried some of their metal, though in sheet form, not casting
grain. The big limit is that the metal only gets a nice black surface
color after a rather hot annealing / heating cycle in air, no fire
coat etc. That means you have to color it before stone setting, and
then the colored areas disrupted by the setting work cannot be
re-colored.


#19

Let me just throw in here that if it is the black that matters and
not the gold in sheet and rod, Niobium is another choice. Heated to a
red hot and air cooled produce a very dark charcoal that is hard and
wears well.

Bill
Reactive Metals Studio, Inc


#20

Sorry, but I don’t understand why anyone would want “black gold”.
Why blacken a beautiful metal? You can have “japanned” metal like
they use in costume, if you want…

Elizabeth Watson
Woburn, MA