Lizzieq wrote "Will you comment on the various (hallmarking)
procedures used in your country?"
In the UK all precious metal goods above certain weights (1 gram for
gold, 7.78 grams for silver and 0.5 grams for platinum ) MUST by law,
be sent to one of the five Assay Offices for testing and marking.
Smaller items can be sent there also if you wish but that is not
mandatory. Before you can submit items to an assay office, you must
have a 'registered sponsor's mark' - your own makers mark, which has
to be sent to the assay office in the form of the actual punches you
are going to use and, at the assay office, these are stamped into
large copper 'record sheets' which the assay office keeps for all
time, your details are entered into the registers and the punches
themselves are stamped with the official assay office crest and a
serial number. Each separate part of an object is tested as is any
solder used and each part receives at least the caratage hallmark.
The main parts also get the full assay office/carat/date letter
mark. In most cases the assay done is still by the old method of
taking scrapings from the metal, weighing them, wrapping them in lead
foil and heating them in a special crucible which absorbs the lead
and the alloying elements in the metal to leave a bead of the
precious metal and then weighing this bead. Comparing the two weights
gives the caratage. For delicate or very small items, they are now
also using an X-ray diffraction machine which gives an accurate
estimation of the metal proportions but this has a disadvantage in
that it only looks at the surface of the metal and so could be fooled
unless used by a very skilled and canny operative. Because of the
physical scraping done to get the metal sample it is usual to submit
work in an unfinished form so that all the parts and the solder to be
used are sent before the piece is finally assembled (this
particularly applies to bigger pieces of plate such as teapots
etc.), also the striking of the assay punches into the metal will, of
course, leave blemishes on plate etc. which will need to be polished
out. A recent development is the use of lasers to apply the hallmark
to delicate objects but this has a disadvantage in that it is only a
surface marking and could easily be removed unlike punch marking
which physically changes the structure of the metal under the mark
such that it could be forensically recreated even if the mark had
been filed out.. Where a batch of similar items are submitted for
assay such as a batch of chains etc., random samples will be taken
and tested - maybe 3 or 4 complete chains out of 100 and the whole
batch marked on the basis of this assay.
The advantages of this method over that practiced in the US is that
it is centrally controlled and entirely out of the hands of the
jewellery maker and is legally required before any item can be sold
as precious metal (unhallmarked silver can only be sold as 'white
metal' for example). The registered sponsors mark allows the maker to
be traced at any time (for hundreds of years either way) and the date
letter is useful in determining the time of manufacture - i.e.
spotting modern reproductions of antique pieces etc. The
disadvantage is that it introduces a delay in the manufacturing
process and additional costs in fees and postage. Whilst some abuses
of the system can take place these are usually confined to
unscrupulous people sawing the hallmark out of a low value piece and
soldering it into a high value piece and can be easily spotted by,
for instance, simply breathing onto the area around the hallmark to
reveal the solder line.
The US system, as I see it, is wide open to abuse and relies totally
on the honesty of the individual. Without actually testing the metal
you start with are you sure the karatage is exactly as the supplier
states or have they sent you the wrong metal? How can you rely on the
makers mark to verify the truth of the marked karatage - it is very
easy to have a spurious marking punch made which wouldn't be
traceable back to you.
Give me the UK system any time, it is 99.99% reliable!
Ian W. Wright