Posthumus: “I praised her as I rated her: so do I my stone.”
“I shall but lend my diamond till you return.”
Iachimo: “My ten thousand ducats are yours: so is your diamond too: if I come off.”
In Act 2, Scene 4, poor Posthumus says:
“All is well yet,
Sparkles this stone as it was wont?”
alluding to the ancient belief that the diamond turned dull when lovers proved unfaithful.
“... The stone’s too hard to come by.”
Iachimo: “I beg but leave to air this jewel: see! it must be married
To that your diamond.”