NGC Authentication Techniques & Tools 3

Question 1

When authenticating ancient coins, what is the significance of 'die axis' measurement?

Accepted Answer

It measures the rotational relationship between obverse and reverse dies, which can indicate period and mint

Answer

Die axis measures how the obverse and reverse designs align rotationally, and consistent die axis orientation can help authenticate coins by matching known mint practices of the period.

Question 2

A suspected counterfeit Morgan dollar shows correct weight and diameter but the reeding appears slightly irregular. What is the most likely explanation?

Accepted Answer

The coin is a cast counterfeit finished with artificial reeding

Answer

Cast counterfeits often display irregular reeding because counterfeiters must add or simulate the edge reeding after casting, making it difficult to exactly replicate the uniformity of genuine collar-struck reeding.

Question 3

Which feature of a coin's luster helps numismatists determine if it was struck with fresh dies versus late-state dies?

Accepted Answer

The flow line intensity and completeness radiating from the design elements

Answer

Fresh dies produce sharp, complete flow lines radiating from design elements into the fields, while late-state dies show weakened or incomplete flow lines due to die wear affecting metal flow during striking.

Question 4

What is 'thumbprinting' in the context of coin authentication?

Accepted Answer

Residue or oils from fingerprints etched into a coin's surface that can cause long-term damage

Answer

Thumbprinting refers to fingerprint residue that has chemically etched into a coin's surface, often visible as permanent marks that can affect grade and sometimes mimic artificial toning.

Question 5

How does NGC use population reports in the authentication process?

Accepted Answer

To track how many examples of a coin have been certified, helping identify unusually high submissions of rare dates

Answer

NGC population reports track the number of coins submitted and certified at each grade, and a sudden surge in submissions of a rare date can be an early warning sign of counterfeiting activity.

(NGC) Numismatic Guaranty Corporation Certified Professional Practice Test

(NGC) Numismatic Guaranty Corporation Certified Professional Practice Test

NGC Authentication Techniques & Tools 3