The term "slab" is slang for a type of holder that third-party grading services use after they professionally grade your coin. There are many advantages to submitting your coins to third party grading services. One of the top reasons is that your coin is housed in the best and most durable coin holder that money can buy.
Third-party Grading Services
Third-party grading services started in the late 1970s and early 1980s in order to provide a professional numismatic opinion of a coin's grade.
During this time many investors started to realize the potential for investing in rare coins. Coin prices were generally on the rise during this time and this appealed to many investors. Unfortunately, many people started calling themselves coin dealers and were selling over graded coins at exorbitant prices to people who are unfamiliar with coin collecting and grading practices.
Third-party grading services hire expert numismatists that examine each and every coin for its authenticity and to provide their expert opinion as to the coin's overall grade. The coin is then sealed into a transparent plastic holder that protects the coin from the environment and physical damage. These holders do not damage the coin in that it is suspended within the holder using an inert plastic insert. Additionally the coin cannot be removed from the holder without damaging or destroying the holder.
This brought stability to the coin collecting market especially for rare and expensive coins.
No longer were buyers dependent upon an opinion from the same party that is selling the coin. Now a third party, that has no vested interest in the transaction, can provide a professional and unbiased opinion as to coin's grade and hence its value.
Slab holders are specially constructed to store rare and expensive coin for extended periods of time.
The inert plastic insert which comes in contact with the coin's edge are specifically engineered so they will not react with the coin's metal. This includes damage from physically coming in contact with the coin and making sure that the plastic insert does not emit any gasses that would cause discoloration or corrosion on the coin's surface.
The outer housing is made from clear hard plastic. Although this plastic does not directly come in contact with the coin's surface, it is also made out of inert material that will not emit gases or in any way react with the coins metal surface. Additionally, the outer plastic housing is made out of high quality plastic that is optically clear and will not discolor over time.
Finally, a label indicating the coin's denomination, year of minting, other identifying characteristics and the professional numismatists opinion of the coin's grade is placed inside the coin holder. This is then sonically sealed which provides a virtually airtight closure between the upper and lower pieces of the outer house.
Any effort to remove the coin or tamper with the indicated grade would become evident on the coin's holder.
Why slab coins
It is highly recommended that any valuable or rare coins be submitted to one of the top-tier third-party grading services (PCGS, NGC, ANACS). In addition to getting a professional numismatists opinion of the coin's grade, you also receive the highest quality holder to protect your coin. Remember, the slightest fingerprint could reduce the value of a rare coin as well as physical damage if the coin is dropped unprotected onto a hard surface.
The major disadvantage to having your coins slabbed is the cost. Costs range from $10 to $30, or more, to submit your coins to a third party professional coin grading service. But the value that you receive back can be priceless. Finally, when it comes time to sell your coins, by you or your heirs, there will be no doubt as to how to determine the value of a coin based upon its type and grade as determined by a professional numismatist.
Read More on: How to Protect, Preserve and Store Your Coin Collection