Higher Powers of Magnification Posted by Skip Fazzari,
Authentication Consultant to NGC, on 5/21/2008
A set of high-magnification hand lenses is an invaluable
tool for numismatists. However, magnification of 10×
and up is only recommended for spotting signs of counterfeiting.
Skip Fazzari offers these tips and more.
There are a host of things to see on coins. No matter what
you are looking for, after a quick perusal, most collectors
will seek some type of magnification to enlarge their view
of the coin they are examining. I travel with an assortment
of hand lenses. There is a 20×, a 10×, and a combination
3×/4×/7×. Beginning with an overall view
to address shape, color, and design, a grader will also be
looking at a coins luster and for imperfections that
detract from its eye appeal. Error/variety collectors will
be looking for doubling on its design, planchet/striking problems,
overdates, and overmintmarks. Authenticators will need to
look more closely at its surface for die polish marks, tooling,
and characteristics common to counterfeit or altered coins.
or five powers of magnification seem to be the norm for many
collectors. At these powers, an entire coin may be viewed
all at once, which is especially useful when grading. Nevertheless,
unless you are an experienced numismatist, you will not be
able to see characteristics such as metal flow, die doubling,
and counterfeit diagnostics on many coins when using minimal
magnification. The micrograph shows the head detail of a genuine
1861-O CSA Obverse Seated half dollar. This view
is close to what you would expect to see when using a 10×
hand lens. The quality of its luster and surface is easily
determined. The diagnostic die break through Libertys
nose is sharp. At this power, a few radial flow lines are
visible at the coins rim and it becomes easier to determine
if any luster breaks on Libertys breast are due to cabinet
friction or friction wear from circulation. Note that at 10×,
you can only view large coins a section at a time. We can
examine the coin for circulation wear but we have narrowed
our field of view considerably, making it more difficult to
judge how any bag marks affect the eye appeal of this specimen.
One well known dealer has told me that at 10× magnification,
You cannot see the forest for the trees. Its
his opinion that this is too much power for coin grading.
Powers of magnification over 10× are best saved for
counterfeit detection. Ten power is also a convenient magnification
for variety hunters. Higher powers may also be used; however,
most micro-doubled dies and any variety needing 20×
to identify may be interesting to find but they are not universally
popular at the moment except by some collectors and specialists.
For example, although the Redbook lists just one
major variety of 1972 Doubled Die cent; I believe variety
collectors have identified more than a dozen varieties of
this cent with smaller amounts of doubling.
While some experienced authenticators can detect a counterfeit
coin using low powers of magnification or even their unaided
eyes, 10× and higher should be the norm for authenticators
who are searching for clues to identify new, state-of-the-art
counterfeits. At these powers, characteristic defects transferred
to the fake by counterfeit dies become apparent.