Brief History
Systems for describing and defining the condition of coins for collectors and dealers appear to have evolved over several hundred years. When we came into the hobby and business in the early 1970's, it seemed that the existing systems had been around for a long time. Publications such as "Seaby's Standard Catalogue of British Coins" contained a page defining 7 basic descriptive coin grades from poor to FDC. By adding the modifiers "almost" or "good", this could easily be expanded to about 20 grades or more. Similarly "The Standard Catalogue of U.S. Coins", published from the 1930s contained comments about grading.
In 1958, Martin R. Brown and John W. Dunn published A Guide to the Grading of United States Coins, which may have been the first book devoted to coin grading, even though it was restricted to US coins. When we first saw it, we wondered what it was about Americans that they needed a book to tell them how to grade every single US coin type, surely if you learn how to grade one type of coin, you know how to grade all coins. Perhaps the answer is that this book did not teach people how to grade coins, it simply showed them US coins of each grade, with notes about what to look for in each type.
Since then, other books about how to grade US coins have been published, notably Photograde, by James F. Ruddy in 1970, and Official ANA Grading Standards for U.S. Coins in 1977.

Grading & Market Prices
According to some sources, in the good old days, there used to be only two grades, used and unused, although others state three grades. We doubt the accuracy of these sources.
What has made grading more important is the growth in the number of collectors, and the increase in the value of most coins. It has always been the case that the desirability and market value of any coin depends on its state of preservation. As market prices have risen

Independent Grading - A Substitute for Judgement?
When independent grading was first introduced, we felt that it was possibly used by buyers as a substitute for their own judgement. We still have this view.
For the vendor, it is another marketing tool. It is very easy as the owner of a coin, to overgrade it, simply because you want it to be better than it is. An independent grade removes the buyer's suspicion that the vendor may have overgraded it deliberately or otherwise.
An independent grader should have no emotional or finincial attachment to the coin, so should be able to be more objective when apprasing it.

Grading & Encapsulation
Grading & encapsulation go hand in hand to some extent. If you are going to buy a high value coin based on its independent grading, and you lacked sufficient intelligence and judgement to form your own opinion, you would presumably need assurance that the coin you were buying was indeed the same coin that had been graded, and that it had not later been switched for an inferior one.

Slabbing
Slabbing is a rather ugly sounding word, but one which is not wholly inappropriate. The expression "indpendently graded and encapsulated" does not quite run easily and quickly off the tongue, while "slabbed" does. It is no surprise then to find that most dealers and collectors refer to "slabbed" coins. Indeed it would have been very surprising if this lingual shortcut had not developed.

PCGS - Professional Coin Grading Service
PCGS, The Professional Coin Grading Service began serving the coin-buying public on February 3, 1986.

How Do Grading Services Rate?
PNG & ICTA Reveal Survey Results

• Numismatic Guaranty Corporation (NGC) and Professional Coin Grading Service (PCGS) were both listed overall as "superior," the second highest ranking on the scale. Accu-Grade (ACG) was listed overall as "unacceptable," the lowest-ranking category on the scale.
• ANACS and Independent Coin Grading Company (ICG) were ranked overall as "average." PCI Coin Grading Service (PCI) and Sovereign Entities Grading Service (SEGS) were ranked overall as "poor."