Stephen L. writes: I recently purchase a number of wheat back Lincoln cents from a dealer on the internet, many were represented as MS 60 to 65. My question is how can you tell if a coin was modified to improve the grade? I have looked at some of them thru a 40X microscope and detected many fine lines. How do you tell if the Mint put them there or if someone else did to improve the coins grade?
There are several kinds of lines one might see on a coin’s surface:
- Flow Lines – These are the result of the tremendous pressure exerted on the flan when it is struck. The lines flow in a radial pattern from the center of the coin to the edges.
- Die Polish – Coin dies need to be removed from the press and rubbed with a diamond dust impregnated cloth to remove debris and to keep the die surfaces smooth. Die polish usually appears as short raised lines on the coin.
- Scratches from cleaning – When a coin is cleaned, fine scratches can be seen on the coin. Because they are inside the coin instead of raised, like die polish, they seem to appear and disappear depending on the angle the coin is viewed at when under strong light. Another way to tell is to check whether these marks appear to cross from the devices into the field.
40x power is a bit much for grading coins, a 4 or 5x slide glass would do better as you can see the whole coin at once. This is most important for purposes of any coin evaluation.
