Counterfeit Detection: Serial Number Error

Posted on 9/15/2020

Blotchy ink on the serial number indicates that this note has been altered to appear like an error.

The note that we are diagnosing this month is a Hong Kong Pick# 401a. This note was issued in 2007 by the government of Hong Kong, China. For such a relatively low-value note – 10 HKD ($1.29 USD) – this little guy has a lot of security features.

Hong Kong Pick# 401a
Click image to enlarge

Normally, this note comes with two serial numbers: one horizontally positioned at the top left and the other vertically aligned at the right. The vertically aligned serial number appears to be insufficiently inked.

Counterfeit Hong Kong Pick# 401a
Click image to enlarge

This already looks problematic. But let’s see if we can find some more evidence to determine whether this note was altered. The first step is to put the note under ultraviolet (UV) light.

Counterfeit Hong Kong Pick# 401a under ultraviolet lighting
Click image to enlarge

This already isn’t what we would expect. But what would we expect? An excellent question. Insufficient inking in a case like this would involve the serial numbering device not being properly inked, leaving one or both of the serial numbers under-inked or not inked at all.

Since the error is insufficient inking – or not being inked fully – we would expect that the serial number’s ink would be even across the entire serial number. Now, this isn’t always the case. Sometimes, not all of the serial number will strike the substrate at the same pressure. This causes some numbers to just kiss the substrate while others will be heavily embossed. More information is needed in this case.

Counterfeit Hong Kong Pick# 401a under infrared lighting
Click image to enlarge

This is a look under infrared (IR) lighting. As you can, see the complete serial number had the same amount of pressure throughout. This would indicate that what we saw in the UV was the serial number being washed away to fake an error. Let’s see if we can find the last nail in the coffin, just to be certain.

For the last check, we zoom in on one of the numbers under normal lighting. Insufficient inking will be gradual and continuous. There won’t be any hard breaks, and the ink won’t appear to bleed or run.

Close-up of counterfeit Hong Kong Pick# 401a
serial number under normal lighting
Click image to enlarge

This is the exact opposite of what an expected insufficient inking would look like. The ‘3’ is blotchy and the ink is running off of the numeral.

This note has been altered to appear like an error. The UV showed us inconsistent reaction, the IR showed us that the serial number had consistent pressure and a close-up of one of the numbers showed us running and blotchy ink patterns. This is consistent with someone using a liquid to remove the visual ink. The normally black ink was washed away, but the UV remained.

Always give the note a careful eye before purchase. It is important for collectors to do their research when purchasing banknotes. However, for those without a personal library of numismatic references, PMG graders will always endeavor to give notes the careful research that they require. As always, any note encapsulated by PMG is backed by our PMG Guarantee of grade and authenticity.

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