You were thinking of an opal.
Can it cheer you up? You said Irrelevant, I say Yes.
Is it considered valuable? You said Depends, I say Yes.
Is it round? You said Depends, I say Yes.
Is it very, very expensive? You said No, I say Yes.
Does it fit in your wallet? You said Doubtful, I say Yes.
Is it usually green? You said Partly, I say No.
Does it refract light? You said No, I say Yes.
Can it be painted? You said Unknown, I say No.
Do you love it? You said No, I say Yes.
It does not matter if our answers disagree, as over time the game will change its answers to reflect common knowledge. If you feel that the game is in error, the only way to fix it is to play again.