Wanna see the SICKEST good luck charm ever??
Good ... 'cause it's hanging around Aaron Donald's neck -- a $250,000 diamond chain that's helped give A.D. the power to be the NFL's top defensive player this season!!!
Shortly after the Rams DL inked his record-breaking $135 MILLION deal in August ... Donald nabbed this custom chain from Moe Diamonds in Pittsburgh.
The ice is INSANE ... TMZ Sports has learned the Miami Cuban chain alone is approximately 3/4 kilo of 14K gold with over 60 carats of true graded VVS-VS colorless diamonds.