Card grading is a complex hence subjective interpretation. No two collectors would probably agree to the same grade for the same card. Because of this, it is one reason for the growth and popularity of "professional" grading companies. Many collectors have trust in this service due to consistency and quality. One Sports columnist has explained that Graded cards have become a hobby staple. A Mint or Gem Mint Graded card adds a premium to any card. In Beckett's case e.g., they provide sub-grades. If two cards have the overall same grade, the one with the higher sub-grades may sell at a higher premium. Here are the Top 30 Graded Cards.
Before submitting your cards for grading, look at the Beckett Grading Scale on how to determine what condition your cards are in before you decide to submit them.
Why should someone buy Graded Cards? Trimming and counterfeiting are problems that face the hobby. Graded cards, from the reputable companies, are a wise investment. Secondly, there are fake cards and/or fake patch cards so you need to be cautious. A fake patch card is a card containing an altered or replaced patch-see link. Beckett Grading Services now offers a Personalized Label option on Grading and Authentication for new and existing customers.
There are four major grading card companies, and there are several other companies.
Besides the major companies there are others that use their own Grading Scale e.g., BSGS, SCD, PRO, PSG, GEM, GMA PGS, PGI, PGC, AAI, AGA, AGS, CCS, CSA, SPA, MGS (Mint Grading Services)GMC, GU, Professional Grading Authority, Premier Grading Co., USA, etc.