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There are many articles on precious metals on the web and some of them are quiet
professional with a lot of details and data. I will try not to give you just
another one. Here I will offer you a simple version and avoiding extensive
technicality add my professional opinion on the best use of these metals in
order to utilize their unique properties. In this article we will focus on the
most popular precious metals used for jewelry: gold, platinum and the fast
growing in popularity palladium.
Pure gold and platinum are soft metals which are extremely dense. pure gold is
about two and half times heavier than iron and pure platinum is just under three
times. While really bright in color pure metals are not suitable for fine
jewelry because of their softness. Soft metals are easy to damage, difficult to
polish, and unsuitable for detailed work. This is why they are mixed (alloyed)
with other metals, in order to give them the desired properties. This is also
where all this “carats” and confusing numbers come into play. In fact it is
pretty simple.
All pure metals in nature are white or gray in color except two, gold – bright
yellow and copper- reddish pink. Now we go back to precious metals.
All different colors of precious metals are achieved by mixing these colored
metals with white ones.
Carat is a confusing name for purity or fineness of precious metals. It is
confusing because the same word is used as a weight measurement for precious
stones. That carat is equal to 0.2gr. and have nothing to do with metal
fineness. To differentiate the one carat from the other, in some standards,
weight carat is marked with ct and purity karat with kt or k. We can accept this
rule to avoid confusion in further articles, therefore when we address metal
purity we will use “karat”. Karat is used mainly to define purity of gold
alloys. Different countries have different standards for gold purity and the
most used globally alloys are: 9kt or 375, 10kt or 416, 14kt or 585, 18kt or
750, 21kt or 875 and 22 or 916. The alternative number which alone can be used
as hallmark indicates the number of fine gold parts in the alloy out of 1000.
The easy way to translate this into a manageable information is to perceive it
as the percentage of fine gold used x10. For example 750 means 75% pure gold
content or 18kt.
Platinum is used in almost pure form and 95% hallmarked 950 is a standard alloy.
All alloys with pure platinum content of 95.0% or higher can be also marked with
the full word “platinum” or “”plat.” Other used alloys are 900 (90%),800 (80%)
and 585(58.5) also called karat platinum. The amazing qualities of this amazing
metal are better described in another article where I am comparing it with the
white gold alternative
Alone or alloyed with 5% ruthenium , palladium offers the same hypoallergenic
and metal working properties as other jewelry metals, and remains tarnish free.
It also offers jewelers a sharply different pricing point than either gold,
white gold or platinum. It is more precious than silver and whiter than
platinum. Because it is also lighter than platinum, nearly half the weight, more
intricate necklaces and bracelets can be made capable of bearing larger
gemstones with no gain in overall weight. For the same reason, Palladium can be
an especially good choice in earrings. With the price of platinum and gold
reaching recent highs, use of palladium for jewelry has seen renewed interest.
The hallmarks you will usually find on your precious metal jewelry are:
1). Karat or fineness stamp (e.g. 18kt/ct or 750)
2) Manufacturer’s stamp
The karat stamp does not have much value without the manufacturers stamp because
the declaration of purity is not signed. Beware; in most countries you can buy a
karat stamp for few dollars.
Variety in gold colors and mechanical properties is achieved by alloying fine
gold with one or more other metals. White gold for example is a gold alloy with
whitening metals, usually palladium, nickel or silver or combination of them.
Since the fine gold is always yellow, it is the alloy (base) metals that give
the karat gold its color and properties. For example to be able to stamp an item
as 18k it must content at least 75% of fine gold. The remaining 25 percent of
alloy metals will determine its color and physical properties. If 8.4% of copper
and 16.6% silver is used in the alloy, we will end up with the traditional rich
18k yellow gold color. If we mix the same amount of fine gold with 15 % of
palladium and 10% of silver we will have good quality white gold. The constant
content in 18k gold alloy is always 75% pure gold. Higher than 18k white gold
alloys are not possible because the alloying metals are not in sufficient
quantity to absorb the yellowness of the pure gold. 21k or 22k gold is always
yellow, very yellow.
The same principle applies for platinum and palladium, although these metals are
used in much purer form (95% is a standard) and there is not detectible changes
in color. The only changes there are in physical properties.
Now, with our newly acquired knowledge of precious metals we will probably
arrive at the questions: What are the best alloys? What metal jewelry should I
buy?
Different metals are good for different purposes. As a general rule (and if you
can afford it) buy alloys with higher precious metal content. That applies
mainly for gold, since platinum and palladium are used in almost pure form. 18kt
gold or higher have distinctive gold color and real precious metal properties.
My opinion is that alloys with less than 50% gold content (under 14k) should not
be called gold, but gold brass or something else defining the inferior gold
content. If you are looking for big bold and heavy pieces the best is to go for
silver with gold accents or the very new precium (25%palladium and silver alloy
developed by Handy & Hartman)which may be already on the market at the time you
read this article. For your fine jewelry pieces choose 18k gold and platinum.
18k white gold can be used for heavier, thicker pieces while platinum is the
best for delicate settings with a lot of detail. It does not make sense to set
$10 000 diamond in white gold just to save $ 300-400 difference on platinum
setting. Besides the aesthetical superiority, the security of platinum setting
is immensely greater. When we come to earrings, especially large ones, choosing
lighter alloys is essential. Palladium is the first choice followed by 14k
white. For yellow, stick to 18k. You can never get the right color in lower
karats. Then, your goldsmith’s ability to work light will come handy. Try to
find the right craftsman. It is really making all the difference. The weight of
the stud settings is rather small even in the case of large diamonds, thus
making the platinum the obvious choice for white metal. The difference in price
will be insignificant but the difference in strength and safety and quality -
vast. Another advantage of the platinum studs – they could be made very delicate
and retain their strength. |
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