They are the cubic zirconia inside the 10 karat gold
That get green on ya, when you get green on em
You gotta wash ya hands of em, get clean on em
Cubic zirconia is a look alike and substitute for diamonds — thus essentially a fake diamond — so to have something so worthless inside of 10 karat gold — which can be quite expensive — would be a massive disappointment. Kanye is using this as a metaphor for the old people referenced in the previous line who kill the dreams of others.
Fake rings also have a tendency to turn the finger of the wearer green over time. This is a double meaning.
1st Meaning: A metaphor for people pretending to be helping you, but actually just being fake.
2nd Meaning: People getting “green”, or jealous, when you get green, which is another term for money.
Just like you would have to wash your hands after a fake ring had turned your finger green, you should “wash your hands”, or stop associating with people who are green with envy.
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