Just as diamonds are graded by professional jewelers based upon their color, cut and clarity, professional coin graders judge circulated coins primarily by the amount of detail removed from the coin as it circulates and wears down.  It’s with uncirculated, or Mint State, coins, however, that coin grading becomes more complex and challenging.  Mint State coin grading is much more sophisticated and requires years of grading experience.  It is one of the major reasons why people turn to Independent Coin Grading.

When grading an uncirculated coin, at least eight factors must be weighed before a final grade can be assigned.  These factors include:  luster, contact marks, strike, color, toning, friction, coin or die flaws and obverse/reverse consolidation.  Many of these contribute to the coin’s overall appearance.  Let’s look at each factor.

Luster is the reaction of light with the microscopic flow lines or die erosion lines on the coin’s surface.  The amount of luster a coin possesses is the major element in determining its eye appeal.  A coin with full original mint luster generally will qualify for higher grades.   Contact marks, or bag marks as they are commonly called, are the dents and scratches that occur on a coin as it comes in contact with other coins during the manufacturing process, or while stored in mint bags.  Contact marks detract from a coin’s grade based upon their location, severity and quantity.  Obviously, the more apparent or severe the marks are, and the more marks there are on the coin, the lower the coin’s grade.   Strike.  Not all coins are struck equally.   Some coins are struck better than others and the strike can vary among coins from the same mint and year of issue.  The stronger the strike, the sharper the coin’s detail and therefore the higher the grade.   Color.  On copper or bronze coins, red color is considered the most original and valuable.  Mint State copper coins are designated as:  RD for Red, RB for Red/Brown and BN for Brown.  Red/Brown toning is less original and brown the least original.  The heavier the toning the lower the value and the designation of copper coins.

Toning is a thin film of sulfide that is sometimes found on the surface of reactive coin metals, especially copper and silver coins.  It is what can cause a coin to have beautiful and subtle hues ranging from blue to magenta to orange to light gold.  However, heavy toning can cause a coin to turn an ugly brown or even black.  Therefore, a coin’s toning can be either attractive and add to its overall grade, neutral and not play a part in the final grade or negative and bring down the coin’s grade  (at Independent Coin Grading, we are the only major grading service that has decided not to grade a coin that has negative eye-appeal or unattractive toning).   Friction is caused by light rub or contact on the coin’s high points.  Even slight friction, or wear, can sometimes lower a coin’s grade from uncirculated or mint state, to circulated.   Coin or die flaws.  There are two major ways that the Mint can make a production mistake.  The first is to strike a coin on a defective planchet.  The second is to strike a coin from a die with defects.  If either of these happens the coins grade can be lowered depending upon the location and severity of the flaw.  However, some mint errors are collectable and increase the coins value.   Obverse/reverse grade consolidation.  The obverse almost always dominates a coin’s value and therefore its grade.  Seldom does a coin’s reverse add or detract significantly to the coin’s ultimate grade.  This is especially true with large portrait coins such as Morgan and Peace dollars.