Mariano's first baseball card, the 1990 Diamond Cards is extremly rare with only 1,100 produced, many of which never hit circultation. Graded a Mint 9 and signed beautifully with a perfect 10 grade. Only two better signed copies are known to exist, one of which is on eBay for $20,000! The best closer of all time, Mariano also added the inscription, "1st Unanimous HOF" which is one of the most amazing accomplishments when you think of all the legends that came before him.

https://www.psacard.com/cert/88374997

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