What are slabs?
A certified coin, or slab, is a coin that has been authenticated, graded and encased in a sonically sealed, hard plastic holder by a professional certification service. The holder affords protection from subsequent wear or damage but is not airtight and therefore will not prevent toning. Because any tampering with the holder will be obvious, it also prevents replacing the certified coin with something else. Counterfeit and altered coins slabbed by major certification services are not unknown but are extremely uncommon. The authenticity of a coin may be guaranteed by the company that slabbed it. Therefore, a coin slabbed by a major certification service offers some protection, especially when fakes are known to exist and the prospective buyer is not able to reliably determine its authenticity. Some certification services will not slab coins that have been altered, whizzed, cleaned (dipping is sometimes acceptable), artificially toned or otherwise damaged. Others certification services w
