Counterfeit Detection: Deciding Whether an Error Is Genuine

Posted on 12/17/2019

PMG experts show how they discover that a note has been altered.

Among collectors' most common questions is — is this error real? This month, we will look at a Singapore 1 dollar note issued in 1987 (Pick 18a, TAN S-1a, KNB 23). This is the lowest denomination in Singapore’s ship series, in which each note features a different vessel. The 1 dollar showcases a sha chuan (Chinese junk) on the front.

PMG has graded 1,580 Singapore 18a notes, with this one being the highest graded.

This note has a doubled printing error on the back that needs further examination. A doubled print error occurs when a portion of the note is printed twice. This can happen in several ways.

A telltale sign of a genuine double print is when the print looks blurry because it was “struck” by the intaglio plate more than once, meaning that the substrate contacted the engraved plate multiple times. This error happens almost exclusively on the intaglio portion of the note. The doubling always will appear on the same side and will be in the same positive orientation, unlike an offset error, which will be mirrored. Because of how this error occurs, the same ink that is applied first is the same ink that is applied during the double (or in very rare cases, the triple) contact with the plate.

It’s hard to tell which is the doubling; we are looking at the part of the design that is touching the left edge of the note.
Compare that to the back of the same type of note without an error.

Here we have clear margins all around the note.

Our first step is to examine the note under magnification.

We know that both “$” should have been printed at the same
time under the same conditions. So, they should look the same.

Even initially, this error doesn’t look convincing. The “$” on the left doesn’t exhibit the same smoothness as the “$” on the right. This is troublesome. If we continue to look at the differences, we see gaps in the print of the “$” of the left.

Let’s continue with the examination to see if we can find more evidence that this note has been tampered with.

Under special lighting, the $ on the right vanishes.

This is the most compelling evidence we found. The design element that is visible under special lighting is the one touching the left edge of the note — the same one that we initially found suspicious.

We know that, if genuine, the error would have occurred at the same time, on the same machine and with the same ink as the rest of the design. Because only one ink is visible under special lighting, we know that the inks are not the same. If they were the same, they would have reacted to the light in the same way.

This error is a fabrication. The person doctoring the note used a blue ink that was close to the original and put the note through a screen lithography press. Evidence for this is indicated in the image below.

Under magnification, the stair steps inthe guilloche pattern become apparent.

It’s easier to see under a high magnification. Notice the stair steps in the guilloche pattern? If you imagine looking through a screen door, you can visualize how this was printed. This print process uses a screen when applying the ink – hence, the name screen lithography — and the result is obvious once you know what to look for.

Identifying a genuine error can be difficult for the untrained eye. Here at PMG, we have experienced graders and equipment to catch alterations made to create errors. Collectors can be assured that any note encapsulated by PMG is backed by the PMG Guarantee of grade and authenticity.


Article List:

PMG Counterfeit Detection Series Wins NLG Award at ANA

A Singapore Serial Number 000001 Brings $400,000 USD

Counterfeit Detection: Phony Specimens Are of No Value

Counterfeit Detection: Altered 1862 Legal Tender

Counterfeit Detection: Altered $5 Note from a US Bank

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